Methods and apparatus for performing knee arthroplasty

ABSTRACT

Methods and apparatus for performing knee arthroplasty, including, but not limited to, bicruciate retaining knee arthroplasty, are described herein. Methods and apparatus for preparing a distal femur for a femoral implant as well as methods and apparatus for preparing a proximal tibia for a tibial implant are described. These methods and apparatus, in at least some embodiments and uses, facilitate decreasing the complexity of knee arthroplasty procedures such as bicruciate retaining procedures, while maintaining, if not improving on, the safety, accuracy and/or effectiveness of such procedures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/790,002, filed May 28, 2010, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/182,435, filed May 29, 2009and titled “Methods and Apparatus for Performing Bicruciate RetainingArthroplasty,” and also claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/299,835, filed Jan. 29, 2010 and titled“Bi-Cruciate Retaining Tibial Implant,” and the entire contents of theprior applications are hereby incorporated by reference herein.

BACKGROUND

Total knee arthroplasty procedures often require the sacrifice of theanterior cruciate ligament (ACL) and the posterior cruciate ligament(PCL). As such, total knee prostheses often include structures andmechanisms that attempt to provide the same or similar functions of theACL and PCL. Some believe, however, that these conventional total kneeprostheses do not fully replicate the normal proprioception, kinematics,and biomechanical function that natural ligaments provide for allpatients. Bicruciate retaining knee replacements have been used in thepast, but were associated with problems of knee stiffness and implantfailure which were likely related to inadequate implant design,instrumentation, and/or implantation technique. Accordingly, there is adesire in some cases to preserve functioning cruciate ligaments in youngand active patients who require knee joint replacement, to maintain anatural feeling, and normal biomechanical function and performance ofthe knee after knee replacement. There is also a need in some cases formore efficient and accurate methods and apparatus for preparing femursand tibias for bicruciate retaining implants (i.e., ACL and PCLpreserving) as well as other types of knee implants, since many kneeprocedures (especially, but not limited to, bicruciate retainingprocedures) often employ methods and apparatus that are less than ideal.

SUMMARY

Methods and apparatus for performing knee arthroplasty procedures,including methods and apparatus useful to total knee arthroplasty (TKA)procedures such as bicruciate retaining arthroplasty and others aredescribed herein.

In some embodiments, there is provided a surgical kit for arthroplastyon a knee joint, the surgical kit comprising at least one distal femoraltrial for evaluating a distal femoral resection of a distal femur,wherein the distal femoral trial comprises a top most, superior, planarsurface for contact with the distal femoral resection; and an inferior,curved surface defining at least one condylar surface for contact withan unresected surface on a proximal tibia. In some embodiments, theinferior, curved surface defines a medial and lateral condylar surfacesfor contact with the unresected surface on the proximal tibia. In someembodiments, the distal femoral trial is a gauge for gauginginternal/external rotation, anterior/posterior position, medial/lateralposition, or size of the distal femoral trial with respect to the distalfemur. In some embodiments, the distal femoral trial includes one ormore references located on the distal femoral trial to indicate anexpected position and orientation of a femoral implant with respect tothe distal femur. In some embodiments, the references are located toindicate a position of the distal femoral trial with respect toposterior medial and posterior lateral edges of the distal femoralresection. In some embodiments, the one or more references forindicating the position of the distal femoral trial with respect toposterior medial and posterior lateral edges of the distal femoralresection comprise posterior edges of the inferior, curved surface ofthe distal femoral trial. In some embodiments, the distal femoral trialincludes one or more references for indicating a position of the distalfemoral trial with respect to a central anterior V point of the distalfemoral resection. In some embodiments, the one or more references forindicating the position of the distal femoral trial with respect to thecentral anterior V point of the distal femoral resection comprise one ormore windows extending through the distal femoral trial. In someembodiments, the distal femoral trial comprises a bicruciate retainingdistal femoral trial. In some embodiments, the distal femoral trial issubstantially U-shaped and defines a gap between the medial and lateralcondylar surfaces for receiving at least a portion of a tibial eminenceon a proximal tibia. In some embodiments, the distal femoral trialsubstantially replicates at least one of a shape, a thickness, and asize of an inferior portion of a bicruciate retaining femoral implant.In some embodiments, the distal femoral trial is part of a set of distalfemoral trials of different sizes of distal femoral trials. In someembodiments, the different sizes of distal femoral trials substantiallyreplicate distal portions of different sizes of femoral implants. Insome embodiments, the distal femoral trial is modular. In someembodiments, the surgical kit comprises a plurality of shims for varyinga thickness of the distal femoral trial. In some embodiments, thesurgical kit comprises a plurality of shims for varying a thickness of alateral condylar portion of the distal femoral trial. In someembodiments, the surgical kit comprises a plurality of shims for varyingat least one of a varus/valgus angle and a flexion/extension angle. Insome embodiments, the distal femoral trial is part of a set of distalfemoral trials of different thicknesses. In some embodiments, the distalfemoral trial is part of a set of distal femoral trials of havingdifferent varus/valgus angles or different flexion/extension angles. Insome embodiments, the surgical kit also includes an alignment block forsecurement to the proximal tibia, wherein the alignment block isconnectable to the distal femoral trial. In some embodiments, thealignment block is connectable to the distal femoral trial in a fixedangular position. In some embodiments, the surgical kit also includes analignment block for securement to the proximal tibia; wherein the distalfemoral trial includes an attachment site for connecting the alignmentblock to the distal femoral trial. In some embodiments, the surgical kitalso includes a connector for connecting the alignment block to thedistal femoral trial in a fixed angular orientation. In someembodiments, the surgical kit also includes a connector for connectingthe alignment block to the distal femoral trial such that a planar benchof the alignment block is parallel to the proximal, planar surface ofthe distal femoral trial. In some embodiments, the surgical kit alsoincludes an indicator for indicating at least one aspect of a proximaltibial resection; wherein the distal femoral trial includes anattachment site for associating the indicator with the distal femoraltrial. In some embodiments, the indicator is for indicating a posteriorslope of the proximal tibial resection, a varus/valgus angle of theproximal tibial resection, or a depth of the proximal tibial resection.

In some embodiments, there is provided a method of performing anarthroplasty on a knee joint having a distal femur and a proximal tibia,the method comprising performing at least one planar distal femoralresection on the distal femur to create at least one resected surface onthe distal femur; inserting a trial between the resected surface on thedistal femur and an unresected surface on the proximal tibia, whereinthe trial contacts the resected surface on the distal femur and theunresected surface on the proximal tibia; and evaluating the distalfemoral resection using the trial. In some embodiments, evaluating thedistal femoral resection using the trial occurs prior to performing atleast one additional box cut on the distal femur. In some embodiments,performing the at least one distal femoral resection comprisesperforming the at least one distal femoral resection prior to performinga proximal tibia resection. In some embodiments, performing the at leastone distal femoral resection prior to performing the proximal tibiaresection comprises performing the at least one distal femoral resectionprior to performing any proximal tibia resections on the proximal tibia.In some embodiments, inserting the trial comprises inserting a distalfemoral trial having a superior, planar surface for contact with the atleast one distal femoral resection and an inferior, curved surface forcontact with the unresected surface on the proximal tibia. In someembodiments, inserting the distal femoral trial comprises inserting adistal femoral trial having a superior, planar surface and an inferior,curved surface that replicates a shape and a thickness of a femoralimplant for installation on the distal femur. In some embodiments, themethod also includes performing at least one additional femoralresection after evaluating the distal femoral resection using the distalfemoral trial. In some embodiments, performing the at least one distalfemoral resection comprises performing the at least one distal femoralresection to a depth that is approximately equal to a distal thicknessof the femoral implant for implantation on the distal femur. In someembodiments, the method also includes re-cutting the at least one distalfemoral resection after evaluating the distal femoral resection usingthe distal femoral trial. In some embodiments, evaluating the distalfemoral resection using the distal femoral trial comprises evaluatingthe knee joint for flexion contracture. In some embodiments, evaluatingthe knee joint for flexion contracture comprises extending the kneejoint and assessing terminal extension. In some embodiments, the methodalso includes inserting a second trial between the resected surface onthe distal femur and the unresected surface on the proximal tibia,wherein the second trial contacts the resected surface on the distalfemur and the unresected surface on the proximal tibia; andre-evaluating the distal femoral resection using the second trial. Insome embodiments, the method of performing the arthroplasty is a methodof performing a bicruciate retaining arthroplasty. In some embodiments,the method also includes, after evaluating the distal femoral resectionusing the distal femoral trial, switching from the method of performingthe bicruciate retaining arthroplasty to a method of performing aposterior cruciate retaining arthroplasty or a method of performing abicruciate sacrificing arthroplasty. In some embodiments, the methodalso includes using the trial to position an alignment block or indiciawith respect to the proximal tibia. In some embodiments, using the trialto position the alignment block or indicia with respect to the proximaltibia comprises: connecting the alignment block to the trial; andsecuring the alignment block to the proximal tibia. In some embodiments,the method also includes connecting the alignment block to the trialusing an intermediate connector. In some embodiments, the method alsoincludes using the trial to position the alignment block in a desiredvarus/valgus angle. In some embodiments, the method also includes usingthe trial to position the alignment block in a desired posterior slopeangle. In some embodiments, the method also includes using the alignmentblock to guide at least one tibial resection after securing thealignment block to the proximal tibia.

In some embodiments, there is provided a femoral cutting assembly forcutting a distal sulcus portion of a distal femur, the femoral cuttingassembly comprising a notched cutter extending along a longitudinalaxis, the notched cutter comprising a leading cutting edge having amedial portion, a lateral portion, and a central portion between themedial and lateral portion, wherein the central portion is substantiallyrecessed into the notched cutter along the longitudinal axis withrespect to the medial and lateral portions; and a femoral cutting guidefor positioning and guiding the movement of the notched cutter along thelongitudinal axis. In some embodiments, the femoral cutting guidecomprises a femoral trial component. In some embodiments, the femoralcutting guide further comprises a modular cutting guide secured in thefemoral trial component. In some embodiments, the leading cutting edgeis a U-shaped leading cutting edge or a V-shaped leading cutting edge.In some embodiments, the notched cutter further comprises at least apair of flanges extending substantially parallel to the longitudinalaxis. In some embodiments, the femoral cutting assembly also includes astop on at least one of the notched cutter and femoral cutting guide,the stop positioned to limit the movement of the notched cutter alongthe longitudinal axis.

In some embodiments, there is provided an assembly for conductingarthroplasty on a knee joint, the assembly comprising a fundamentalinstrument configured to be secured with respect to a proximal tibia ofthe knee joint, the fundamental instrument including a bench having abench connector configured to be oriented at a neutralanterior/posterior slope and a neutral varus/valgus angle relative tothe proximal tibia when secured with respect to the proximal tibia; andan adjustment instrument configured to be coupled to the fundamentalinstrument, the adjustment instrument comprising: a receiver structureconfigured to connect to the bench connector of the fundamentalinstrument in a manner that permits at least one of an angularadjustment of the adjustment instrument relative to the fundamentalinstrument in internal/external rotation and a translational adjustmentof the adjustment instrument relative of the fundamental instrument inmedial/lateral position, the receiver structure including an alignmentaxis; a cutting guide connector oriented at a predetermined slope anglerelative to the receiver structure alignment axis, the cutting guideconnector configured to connect to a cutting guide; whereby the assemblyis configured to permit orientation of the cutting guide connectorrelative to the proximal tibia in at least medial/lateral translation orat least one of the following angulations when the adjustment instrumentis connected to the fundamental instrument: neutral varus/valgus;predetermined slope; desired internal/external rotation. In someembodiments, the adjustment instrument includes structure for adjustablyorienting and fixing slope angle of the cutting guide connector relativeto the receiver structure alignment axis. In some embodiments, theadjustment instrument includes structure for adjustably orienting andfixing internal/external rotation of the cutting guide connectorrelative to the receiver structure alignment axis. In some embodiments,adjustment instrument includes structure for adjustably orienting andfixing medial/lateral position of the cutting guide connector relativeto the receiver structure alignment axis. In some embodiments, thecutting guide connector includes at least one rail for connection to thecutting guide, the rail configured to align in at least one of thefollowing angulations relative to the tibia of the patient:predetermined neutral varus/valgus; predetermined slope angle; desiredmedial/lateral translation; and desired internal/external rotation. Insome embodiments, the assembly is configured to permit simultaneousadjustment of the adjustment instrument on the fundamental instrument inmedial/lateral translation, anterior/posterior translation, andinternal/external rotation. In some embodiments, the adjustmentinstrument is one of a set of adjustment instruments, at least some ofthe adjustment instruments having different predetermined slope angles.

In some embodiments, there is provided an alignment block for conductingarthroplasty on a knee joint, comprising: a body configured to besecured to an anterior surface on a tibia proximate to a tubercle of thetibia; an extramedullary rod connector coupled to the body, theextramedullary rod connector configured to be releasably fixed to anextramedullary rod that is aligned with an anatomical axis of the tibiain a sagittal plane of the tibia, without the body being aligned withthe anatomical axis of the tibia in the sagittal plane; (c) a benchconnected to a superior portion of the body, the bench being generallyplanar in shape to define a bench connector that is substantiallyperpendicular to a longitudinal axis of the extramedullary rod when theextramedullary rod is fixed to the extramedullary rod connector, thebench connector configured to be oriented at a neutral posterior slopeand a neutral varus/valgus angle relative to the proximal tibia when thebody is secured to the tibia and the extramedullary rod connector isfixed to the extramedullary rod that is aligned with the anatomical axisof the proximal tibia in the sagittal plane. In some embodiments, thebench is adjustably connected to the body in a manner that permits thebench connector to be adjusted and releasably fixed in a superior orinferior direction relative to the proximal tibia. In some embodiments,the extramedullary rod connector is configured to be adjustably andreleasably fixed to the body. In some embodiments, the extramedullaryrod connector is configured to be coupled to the bench. In someembodiments, the extramedullary rod connector is configured to becoupled to an inferior portion of the body. In some embodiments, thebench connector includes a plurality of index features configured topermit replicatable coupling of other structures to the bench connector.In some embodiments, the body further comprises openings configured topermit at least two pins to be placed in the tibia in a manner thatpermits the pins, when so placed, to store information about neutralposterior slope and neutral varus/valgus angle relative to the tibia.

In some embodiments, there is provided a cutting guide assembly forconducting arthroplasty on a knee joint, comprising: a navigationinstrument configured to be directly or indirectly connected to aproximal tibia, the navigation instrument including a cutting guideconnector that can be oriented in at least the following angulationsrelative to the proximal tibia: neutral varus/valgus; predeterminedanterior/posterior slope; desired medial/lateral translation; anddesired internal/external rotation; and a medial tibial resectioncutting guide, comprising: a support connection configured to connectthe medial tibial resection cutting guide to the cutting guide connectorof the navigation instrument; a medial cutting guide surface configuredto guide a cutting or milling instrument to remove a medial portion ofthe proximal tibia, the medial cutting guide surface oriented on themedial tibial resection cutting guide in substantially the sameangulations as the cutting guide connector of the navigation instrument;and a medial resection opening and a lateral resection opening, theopenings oriented in the medial tibial resection cutting guide insubstantially the same angulations as the cutting guide connector of thenavigation instrument, each opening configured to guide formation of abore in the proximal tibia. In some embodiments, the support connectionis configured to connect to the cutting guide connector of thenavigation instrument in a manner that permits slidable adjustment ofthe medial tibial resection cutting guide relative to the navigationinstrument, and that permits releasable fixation of the medial tibialresection cutting guide relative to the navigation instrument at adesired adjustment. In some embodiments, the medial and lateralresection openings substantially define a width and an internal/externalangulation of an eminence on the proximal tibia to which eminence atleast one ligament is attached.

In some embodiments, there is provided a stylus for conductingarthroplasty on a knee joint, the stylus comprising: a body configuredto connect to instrumentation, the instrumentation configured to connectto at least one of a proximal tibia or a distal femur, the body defininga reference plane and a connection axis that is perpendicular to thereference plane; a first indicator member that is pivotally mounted tothe body, the first indicator member configured to rotate about theconnection axis in a plane that is substantially parallel to thereference plane of the stylus body; a second indicator member that ispivotally mounted to the body, the second indicator member configured torotate about the connection axis in a plane that is substantiallyparallel to the reference plane of the stylus body; a stylus connectorconnected to the body, the stylus connector configured to locate thereference plane of the stylus in a predetermined position andorientation relative to the instrumentation. In some embodiments, atleast one of the indicator members is rotatable to a position thatindicates orientation of the instrumentation relative to the proximaltibia in at least internal/external rotation. In some embodiments, atleast one of the indicator members is rotatable to a position thatindicates orientation of the instrumentation relative to the proximaltibia and distal femur in at least varus/valgus angulation. In someembodiments, at least one of the indicator members includes a guidesurface for guiding instrumentation to cut or mill a portion of theproximal tibia proximate an eminence on the proximal tibia, to whicheminence at least one ligament is attached. In some embodiments, theindicator members are configured to generally indicate the position,width and angular orientation of an eminence to be formed on theproximal tibia, to which eminence at least one ligament is attached. Insome embodiments, at least one of the indicator members is configured togenerally indicate alignment of the proximal tibia relative to thedistal femur. In some embodiments, the stylus is configured to connectto a cutting guide. In some embodiments, the stylus is configured toconnect to instrumentation other than a cutting guide. In someembodiments, the stylus is configured to connect to instrumentation thatis connected to the distal femur. In some embodiments, the stylus isconfigured to connect to instrumentation that is connected to theproximal tibia and instrumentation that is connected to the distalfemur. In some embodiments, the stylus is configured to connect toinstrumentation that is connected to the proximal tibia of the patient.

In some embodiments, there is provided a stylus for conductingarthroplasty on a knee joint, the stylus comprising: a body, the bodyincluding a stylus connector configured to connect to a navigationconnector on instrumentation that is configured to be connected to aproximal tibia, the navigation connector on the instrumentationconfigured to be oriented relative to the proximal tibia in at least thefollowing angulations when the instrumentation is connected to theproximal tibia: neutral varus/valgus angulation; predetermined posteriorslope; and desired internal/external rotation; the body defining areference plane and a connection axis that is perpendicular to thereference plane, the reference plane in alignment with at least thedesired internal/external angulation of the navigation connector of theinstrumentation when the body is connected to the instrumentation; afirst indicator member that is pivotally mounted to the body, the firstindicator member configured to rotate about the connection axis in aplane that is substantially parallel to the reference plane of thestylus body; a second indicator member that is pivotally mounted to thebody, the second indicator member configured to rotate about theconnection axis in a plane that is substantially parallel to thereference plane of the stylus body; whereby at least one indicatormember is movable to a position that indicates orientation of theinstrumentation relative to the proximal tibia in at least one ofinternal/external rotation and medial/lateral translation. In someembodiments, the stylus includes a stylus connector that is configuredto connect to a cutting guide. In some embodiments, the stylus includesa stylus connector that is configured to connect to instrumentationother than a cutting guide. In some embodiments, the stylus is furtherconfigured to connect to instrumentation that is connected to a distalfemur. In some embodiments, the stylus is further configured to connectto instrumentation that is connected to an extramedullary rod that isconnected to the patient. In some embodiments, wherein at least one ofthe indicator members is rotatable to a position that indicatesorientation of the instrumentation relative to a knee of the patient inat least varus/valgus angulation. In some embodiments, wherein at leastone of the indicator members includes a guide surface for guidinginstrumentation to cut or mill a portion of the proximal tibia adjacentan eminence, to which eminence at least one ligament is attached. Insome embodiments, the guide surface is configured to prevent cutting ormilling of the eminence and the at least one ligament. In someembodiments, the indicator members are configured to generally indicatethe position, width and angular orientation of an eminence to be formedon the proximal tibia, to which eminence at least one ligament isattached. In some embodiments, at least one indicator member isconfigured to generally indicate alignment of the proximal tibiarelative to a distal femur.

In some embodiments, there is provided a method for conductingarthroplasty on a knee joint, the knee joint including a distal femurand a proximal tibia, the method comprising: positioning a stylus withrespect to the knee joint, the stylus comprising: a body defining areference plane and a connection axis that is perpendicular to thereference plane; a first indicator member pivotally mounted to the body,the first indicator member configured to rotate about the connectionaxis in a plane that is substantially parallel to the reference plane ofthe stylus body; and a second indicator member pivotally mounted to thebody, the second indicator member configured to rotate about theconnection axes in a plane that is substantially parallel to thereference plane of the stylus body; and using the stylus to assessalignment. In some embodiments, using the stylus to assess alignmentcomprises using the stylus to assess alignment of the distal femur withrespect to the proximal tibia. In some embodiments, using the stylus toassess alignment of the distal femur with respect to the proximal tibiacomprises using the stylus to assess alignment of a femoral trial withrespect to the proximal tibia. In some embodiments, positioning thestylus with respect to the knee joint comprises connecting the stylus toan instrument secured to the proximal tibia; and wherein the methodfurther comprises positioning at least one of the first and secondindicator members proximate the femoral trial. In some embodiments,positioning at least one of the first and second indicator membersproximate the femoral trial comprises positioning at least one of thefirst and second indicator members proximate an intracondylar notch oran anterior trochlear groove on the femoral trial. In some embodiments,positioning one of the first and second indicator members proximate atubercle on the proximal tibia. In some embodiments, using the stylus toassess alignment comprises connecting at least one of the first andsecond indicator members to a femoral trial on the distal femur andusing the stylus connected to the femoral trial to align an instrumentassociated with the proximal tibia. In some embodiments, using thestylus connected to the femoral trial comprises using the stylusconnected to the femoral trial to align a tibial resection guideassociated with the proximal tibia. In some embodiments, using thestylus to assess alignment comprises using the stylus to assessalignment of a tibial resection guide with respect to an eminence on theproximal tibia. In some embodiments, the method also includespositioning the first indicator member on a medial side of the eminence;and positioning the second indicator member on a lateral side of theeminence. In some embodiments, the method also includes using the stylusto guide at least one vertical resection into the proximal tibia.

In some embodiments, there is provided a lateral resection cutting guidefor conducting knee surgery, the lateral resection cutting guidecomprising: a lateral resection cutting guide body; a paddle connectedto the lateral resection cutting guide body, the paddle including asubstantially planar surface that is configured to be positioned on asubstantially planar medial resection that has been formed on a tibia;and a lateral resection cutting guide member connected to the lateralresection cutting guide body, the lateral resection cutting guide memberhaving a substantially planar lateral resection cutting guide surface,the lateral resection cutting guide surface configured to guide acutting or milling instrument to form a lateral resection in the tibiathat is referenced from the medial resection. In some embodiments, thelateral resection cutting guide surface is configured to guide thecutting or milling instrument such that the lateral resection in thetibia is co-planar with the medial resection in the tibia. In someembodiments, the lateral resection cutting guide body includes a flagpin receiving opening, the flag pin receiving opening configured toreceive a flag pin inserted into a lateral resection navigation openingformed in the tibia, the navigation resection opening oriented withrespect to the tibia at a predetermined anterior/posterior slope, adesired internal/external rotation, and a desired medial/lateralposition; wherein the flag pin receiving opening lies in a plane that issubstantially parallel to the substantially planar surface of thepaddle. In some embodiments, the flag pin receiving opening includes aplanar portion, the planar portion oriented in a plane that is generallyparallel to the substantially planar surface of the paddle, the planarportion configured to cooperate with the flag pin and assist inorienting the lateral resection cutting guide, relative to the flag pin.In some embodiments, the flag pin receiving opening forms a boundary tothe lateral resection cutting guide surface and is configured topreclude cutting or milling into an eminence on the tibia to which atleast one ligament is attached. In some embodiments, at least a portionof the flag pin receiving opening is configured to be oriented at apredetermined angle relative to a longitudinal axis of the lateralresection navigation opening, and thereby configured to permit thecutting guide to be inserted onto the flag pin at the predeterminedangle relative to the longitudinal axis of the lateral resectionnavigation opening in order to reduce contact with soft tissue on alateral side of the knee during such insertion.

In some embodiments, there is provided a tibial plateau resection guide,comprising: a cutting block defining a horizontal guide for guiding atibial plateau resection; and an elongated flag pin for positioning thecutting block with respect to a proximal tibia, the flag pin extendingalong a longitudinal axis and including an enlarged head portion;wherein the cutting block defines an opening for receiving at least aportion of the enlarged head such that the cutting block cannot rotateabout the longitudinal axis of the flag pin when the enlarged headportion is positioned in the opening in the cutting block. In someembodiments, the enlarged head portion of the elongated flag pin issubstantially planar, and facilitates translation and rotation of thecutting block with respect to the elongated flag pin in at least oneplane. In some embodiments, the at least one substantially planarsurface of the flag pin is substantially parallel to a guide surface ofthe horizontal guide of the cutting block when the enlarged head portionis positioned in the opening in the cutting block. In some embodiments,at least a portion of the flag pin defines a second guide for guidingthe tibial plateau resection when the enlarged head portion ispositioned in the opening in the cutting block. In some embodiments, thesecond guide of the flag pin is positioned to limit movement of a cutterin a mesial direction when the enlarged head portion is positioned inthe opening in the cutting block. In some embodiments, the second guideof the flag pin is defined by the enlarged head portion and an elongatedinsertion portion of the flag pin. In some embodiments, portions of thesecond guide of the flag pin are positioned to prevent movement of acutter into anterior and mesial aspects of a tibial eminence of thetibial plateau when the enlarged head portion is positioned in theopening in the cutting block. In some embodiments, the cutting blockfurther comprises a reference for referencing a second tibial plateauresection, the reference including an inferior planar reference surface.In some embodiments, the horizontal guide comprises an inferior planarguide surface, and wherein the inferior planar guide surface issubstantially coplanar to the inferior planar reference surface. In someembodiments, the horizontal guide is a lateral horizontal guideconfigured for guiding a lateral resection and wherein the referencecomprises a medial reference configured for referencing a medialresection. In some embodiments, the cutting block can rotate about atleast a second axis and can translate in at least one direction when theenlarged head portion is positioned in the opening in the cutting block.

In some embodiments, there is provided a kit of tibial trials for use inperforming an arthroplasty on a knee joint having a distal femur and aproximal tibia, the kit comprising: a first tibial trial for positioningwith respect to the distal femur and a first resected surface on theproximal tibia, the first tibial trial at least partially simulating afirst tibial implant implanted on the first resected surface of theproximal tibia; and a second tibial trial for positioning with respectto the distal femur and the first resected surface on the proximaltibia, the second tibial trial at least partially simulating the firsttibial implant implanted on a second resected surface of the proximaltibia. In some embodiments, the first tibial trial is thicker than thesecond tibial trial and the first tibial trial has a different posteriorslope than the second tibial trial. In some embodiments, the firsttibial trial is thicker than the second tibial trial or the first tibialtrial has a different posterior slope than the second tibial trial. Insome embodiments, the second tibial trial simulates a recut of theproximal tibia, the recut defining the second resected surface, whereinthe second resected surface is distal to the first resected surface. Insome embodiments, the second tibial trial simulates a recut of theproximal tibia, the recut defining the second resected surface, whereinthe second resected surface has a posterior slope that is different froma posterior slope of the first resected surface. In some embodiments,the first tibial trial is for positioning with respect to a femoraltrial on the distal femur and the second tibial trial is for positioningwith respect to the femoral trial on the distal femur. In someembodiments, the first and second tibial trials each include a proximalarticulation surface for articulation with the femoral trial. In someembodiments, the first and second tibial trials each include a medialsuperior articulation surface for articulation with a medial condyle ofthe femoral trial. In some embodiments, the kit also includes a handlefor connecting to the first and second tibial trials. In someembodiments, the handle includes a planar inferior surface forcontacting the resected surface on the proximal tibia. In someembodiments, the first tibial trial includes a superior articularsurface for replicating a position and orientation of a superiorarticular surface of the first tibial implant when implanted on thefirst resected surface of the proximal tibia. In some embodiments, thesecond tibial trial includes a superior articular surface forreplicating a position and orientation of the superior articular surfaceof the first tibial implant when implanted on the second resectedsurface of the proximal tibia. In some embodiments, the kit alsoincludes a third tibial trial that includes a superior articular surfacefor replicating a position and orientation of a superior articularsurface of a second tibial implant when implanted on the first resectedsurface of the proximal tibia. In some embodiments, the second tibialimplant has a different thickness than the first tibial implant. In someembodiments, the second tibial implant has a different posterior slopethan the first tibial implant.

In some embodiments, there is provided a method of performing anarthroplasty on a knee joint having a distal femur and a proximal tibia,the method comprising: resecting one of a medial or a lateral portion ofthe proximal tibia to define a first resected surface; positioning afirst tibial trial with respect to the first resected surface and thedistal femur; evaluating the first resected surface using the firsttibial trial; and after evaluating the first resected surface using thefirst tibial trial, resecting the other of the medial or lateral portionof the proximal tibia. In some embodiments, evaluating the firstresected surface using the first tibial trial comprises articulating thedistal femur with respect to the proximal tibia. In some embodiments,evaluating the first resected surface using the first tibial trialcomprises articulating a femoral trial with respect to the first tibialtrial. In some embodiments, positioning the first tibial trial withrespect to the first resected surface and the distal femur comprisespositioning the first tibial trial with respect to the first resectedsurface and the distal femur to simulate a first tibial implantimplanted on the proximal tibia. In some embodiments, positioning asecond tibial trial with respect to the first resected surface and thedistal femur before resecting the other of the medial or lateralportions of the proximal tibia. In some embodiments, positioning thesecond tibial trial with respect to the first resected surface comprisessimulating a re-cut of the one of the medial or lateral portions of theproximal tibia to define a second resected surface. In some embodiments,the method also includes re-cutting the one of the medial or lateralportions of the proximal tibia to define the second resected surfacebefore resecting the other of the medial or lateral portions of theproximal tibia. In some embodiments, positioning the second tibial trialwith respect to the first resected surface comprises simulating a secondtibial implant implanted on the proximal tibia. In some embodiments,simulating the second tibial implant comprises simulating a tibialimplant having a different thickness than the first tibial implant. Insome embodiments, simulating the second tibial implant comprisessimulating a tibial implant having a different posterior slope than thefirst tibial implant.

In some embodiments, there is provided a method of performing anarthroplasty on a knee joint having a distal femur and a proximal tibia,the method comprising: resecting at least one of a medial or a lateralportion of the proximal tibia to define a first resected surface;positioning a first tibial trial with respect to the first resectedsurface and the distal femur; evaluating the first resected surfaceusing the first tibial trial; positioning a second tibial trial withrespect to the first resected surface and the distal femur; andsimulating a re-cut of the at least one of the medial or lateralportions of the proximal tibia to define a second resected surface. Insome embodiments, evaluating the first resected surface using the firsttibial trial comprises articulating the distal femur with respect to theproximal tibia. In some embodiments, evaluating the first resectedsurface using the first tibial trial comprises articulating a femoraltrial with respect to the first tibial trial. In some embodiments,evaluating the first resected surface comprises evaluating the balanceof the knee joint in flexion and extension. In some embodiments,simulating the re-cut comprises simulating a re-cut at least one of adifferent posterior slope or a different resection depth. In someembodiments, positioning the first tibial trial with respect to thefirst resected surface and the distal femur comprises positioning thefirst tibial trial with respect to the first resected surface and thedistal femur to simulate a first tibial implant implanted on theproximal tibia. In some embodiments, the method also includes, afterevaluating the first resected surface using the first tibial trial,resecting the other of the at least one of the medial or lateral portionof the proximal tibia.

In some embodiments, there is provided a reciprocating bone cuttingdevice, comprising: a first reciprocating bone cutting blade; a secondreciprocating bone cutting blade; and a connector connecting the firstand second reciprocating bone cutting blades together. In someembodiments, the first and second reciprocating bone cutting blades areelongated and each includes a proximal end and a distal end; and theconnector connects the first and second reciprocating bone cuttingblades together proximate the proximal end of each blade. In someembodiments, the first and second reciprocating bone cutting blades areonly connected together proximate the proximal end of each reciprocatingbone cutting blade. In some embodiments, the first and secondreciprocating bone cutting blades each define a cutting plane, thecutting planes extending substantially parallel to one another. In someembodiments, the first and second reciprocating bone cutting blades arebiased towards one another. In some embodiments, each of the first andsecond reciprocating bone cutting blades include an inner, planarsurface. In some embodiments, the inner, planar surfaces of the firstand second reciprocating bone cutting blades are substantially smooth.In some embodiments, the first and second reciprocating bone cuttingblades are removably connected to the connector. In some embodiments,the connector includes an attachment feature for securing thereciprocating bone cutting device in a reciprocating saw. In someembodiments, each of the first and second reciprocating bone cuttingblades includes an attachment feature for securing the reciprocatingbone cutting blades in the reciprocating saw. In some embodiments, theattachment features of the reciprocating bone cutting blades aresubstantially the same size and shape as the attachment feature of theconnector. In some embodiments, the first and second reciprocating bonecutting blades are integral with the connector. In some embodiments, thefirst and second reciprocating bone cutting blades are positioned andoriented with respect to one another to facilitate making two cuts in aproximal tibia at the same time. In some embodiments, the first andsecond reciprocating bone cutting blades are positioned and orientedwith respect to one another to facilitate making two vertical eminencecuts in a proximal tibia at the same time.

In some embodiments, there is provided a bicruciate retaining tibialbaseplate, comprising: a medial baseplate web; a lateral baseplate web;and a bridge connecting the medial and lateral baseplate webs; whereinthe bicruciate retaining tibial baseplate defines a gap between themedial baseplate web and the lateral baseplate web, the gap being sizedand positioned to receive a tibial eminence including an anteriorcruciate ligament attachment site and a posterior cruciate ligamentattachment site. In some embodiments, the medial and lateral baseplatewebs each define substantially planar inferior surfaces for referencingmedial and lateral tibial plateau resections respectively; wherein thesubstantially planar inferior surfaces are substantially co-planar. Insome embodiments, the medial baseplate web includes at least one medialattachment site for securing a medial tibial trial insert; wherein thelateral base plate web includes at least one lateral attachment site forsecuring a lateral tibial trial insert. In some embodiments, thebicruciate retaining tibial baseplate defines a punch gap for receivinga punch including a medial punching surface and a lateral punchingsurface. In some embodiments, the punch gap is for receiving asubstantially U-shaped punch; wherein a first leg of the U-shaped punchincludes the medial punching surface and a second leg of the U-shapedpunch includes the lateral punching surface. In some embodiments, thebaseplate also includes at least one punch guide attachment site forsecuring a punch guide to the bicruciate retaining tibial baseplate. Insome embodiments, the bicruciate retaining tibial baseplate defines ananterior plateau resection gap for receiving a cutter for resecting ananterior aspect of the tibial eminence. In some embodiments, theanterior plateau resection gap is a slot extending through the bridge.In some embodiments, the bicruciate retaining tibial baseplate defines apunch gap for receiving a substantially U-shaped punch including amedial punching surface and a lateral punching surface. In someembodiments, the baseplate also includes at least one guide attachmentsite for securing a guide for guiding the U-shaped punch and the cutterfor resecting the anterior aspect of the tibial eminence.

In some embodiments, there is provided a method of performing abicruciate retaining arthroplasty on a knee joint having a distal femurand a proximal tibia, the method comprising: resecting medial andlateral portions of the proximal tibia around a tibial eminence todefine resected medial and lateral portions of the tibia; positioning atibial trial on the resected medial and lateral portions of the proximaltibia; and after positioning the tibial trial on the resected medial andlateral portions of the proximal tibia, removing an anterior aspect ofthe tibial eminence. In some embodiments, the method also includes,before removing the anterior aspect of the tibial eminence, evaluatingthe resected medial and lateral portions of the proximal tibia using thetibial trial. In some embodiments, evaluating the resected medial andlateral portions of the tibia comprises evaluating a range of motion ofthe knee joint. In some embodiments, evaluating the range of motion ofthe knee joint comprises articulating a femoral trial with respect tothe tibial trial. In some embodiments, resecting medial and lateralportions of the proximal tibia comprises making a horizontal medialtibial plateau resection and a horizontal lateral tibial plateauresection. In some embodiments, resecting medial and lateral portions ofthe proximal tibia further comprises making a vertical medial resectionand a vertical lateral resection. In some embodiments, the method alsoincludes punching a keel cavity into the proximal tibia. In someembodiments, punching the keel cavity occurs before or after removingthe anterior aspect of the tibial eminence. In some embodiments,removing the anterior aspect of the tibial eminence comprises making ahorizontal cut and a vertical cut on the anterior aspect of the tibialeminence. In some embodiments, the method also includes securing a guidewith respect to the tibial trial. In some embodiments, securing theguide with respect to the tibial trial comprises securing a guide forguiding the steps of punching the keel cavity and making the horizontalcut and the vertical cut on the anterior aspect of the tibial eminence.In some embodiments, positioning the tibial trial on the resected medialand lateral portions of the proximal tibia comprises securing the tibialtrial to the proximal tibia. In some embodiments, securing the tibialtrial to the proximal tibia comprises pinning the tibial trial to theresected medial and lateral portions of the proximal tibia. In someembodiments, securing the tibial trial to the proximal tibia comprisessecuring the tibial trial to a component secured to an anterior surfaceof the proximal tibia.

In some embodiments, there is provided a bicruciate retaining tibialtrial baseplate, comprising: a medial baseplate web, wherein the medialbaseplate web includes a medial, mesial reference surface forillustrating an extent of a medial, mesial surface of a bicruciateretaining tibial implant, wherein the medial baseplate web includes amedial, outer reference surface for illustrating an extent of a medial,outer surface of the bicruciate retaining tibial implant; a lateralbaseplate web, wherein the lateral baseplate web includes a lateral,mesial reference surface for illustrating an extent of a lateral, mesialsurface of the bicruciate retaining tibial implant, wherein the lateralbaseplate web includes a lateral, outer reference surface forillustrating an extent of a lateral, outer surface of the bicruciateretaining tibial implant; and a bridge connecting the medial and lateralbaseplate webs; wherein the bicruciate retaining tibial trial baseplatedefines at least one datum site for recording a final desired positionof the bicruciate retaining tibial implant. In some embodiments, thedatum site is a pair of apertures for receiving bone pins. In someembodiments, the datum site is an attachment site for a guide. In someembodiments, the datum site is an attachment site for a punch guide. Insome embodiments, the datum site is an attachment site for an eminenceresecting guide. In some embodiments, the datum site is an attachmentsite for a punch and eminence resecting guide. In some embodiments, themedial, mesial reference surface is a first portion of an arm definingthe medial baseplate web and the medial, outer reference surface is asecond portion of the arm defining the medial baseplate web; and whereinthe lateral, mesial reference surface is a first portion of an armdefining the lateral baseplate web and the lateral, outer referencesurface is a second portion of the arm defining the lateral baseplateweb. In some embodiments, the arms defining the medial and lateralbaseplate webs are structured to receive medial and lateral tibial trialinserts respectively. In some embodiments, outer surfaces of the armsillustrate an outer shape of the bicruciate retaining tibial implant. Insome embodiments, the outer surfaces of the arms illustrate a positionof a gap in the bicruciate retaining tibial implant for receiving atibial eminence having attachment sites for an anterior cruciateligament and a posterior cruciate ligament.

In some embodiments, there is provided a bone removal tool for creatinga keel cavity in a proximal tibia, the bone removal tool comprising: abone removal instrument for defining the keel cavity in the proximaltibia; and a guide for guiding the movement of the bone removalinstrument into the proximal tibia, the guide comprising: at least onesubstantially planar reference surface for referencing a medial plateauresection and a lateral plateau resection on the proximal tibia; asloped guide extending at a non-perpendicular angle to the at least onesubstantially planar reference surface, the sloped guide shaped tointeract with the bone removal instrument to guide the bone removalinstrument at the non-perpendicular angle into the proximal tibia. Insome embodiments, the bone removal instrument includes at least onecutting edge. In some embodiments, the at least one cutting edge has asubstantially U-shaped cross section. In some embodiments, the slopedguide extends at an angle that is non-perpendicular to the at least onesubstantially planar reference surface and at an angle that is obtuse tothe at least one substantially planar reference surface. In someembodiments, the sloped guide includes a capture surface forconstraining the movement of the bone removal instrument. In someembodiments, the bone removal instrument includes an elongatedprotrusion; and wherein the capture surface captures the elongatedprotrusion. In some embodiments, the at least one substantially planarreference surface is an inferior surface of a bicruciate retainingtibial trial baseplate. In some embodiments, the bicruciate retainingtibial trial baseplate defines a gap between a medial baseplate web anda lateral baseplate web, the gap being sized and positioned to receive atibial eminence including an anterior cruciate ligament attachment siteand a posterior cruciate ligament attachment site. In some embodiments,the guide further comprises a horizontal guide positioned and orientedfor guiding the movement of a second cutter into an anterior portion ofthe tibial eminence in a plane that is substantially parallel orco-planar to the inferior surface of the bicruciate retaining tibialtrial baseplate. In some embodiments, the guide further comprises avertical guide positioned and oriented for guiding the movement of asecond cutter into an anterior portion of the tibial eminence in a planethat is not substantially parallel to the inferior surface of thebicruciate retaining tibial trial baseplate.

In some embodiments, there is provided a bone removal tool for removingan anterior portion of a tibial eminence on a proximal tibia, the boneremoval tool comprising: at least one bone removal instrument forremoving the anterior portion of the tibial eminence; and a guide forguiding the movement of the bone removal instrument into the proximaltibia, the guide comprising: a substantially planar medial referencesurface for referencing a medial plateau resection on the proximaltibia; and a substantially planar lateral reference surface forreferencing a lateral plateau resection on the proximal tibia; and ahorizontal guide positioned to guide the movement of the bone removalinstrument into an anterior portion of the tibial eminence in a planethat is substantially parallel to or coplanar with the substantiallyplanar medial and lateral reference surfaces; wherein the guide definesa gap between the medial and lateral reference surfaces, the gap beingsized and positioned to receive portions of the tibial eminence thatinclude at least an anterior cruciate ligament attachment site. In someembodiments, the guide further comprises a vertical guide positioned toguide the movement of a second bone removal instrument into the anteriorportion of the tibial eminence in a plane that is not substantiallyparallel to or coplanar with the substantially planar medial and lateralreference surfaces. In some embodiments, the guide further comprises avertical guide positioned to guide the movement of the bone removalinstrument into the anterior portion of the tibial eminence in a planethat is not substantially parallel to or coplanar with the substantiallyplanar medial and lateral reference surfaces. In some embodiments, thevertical guide is positioned to guide the movement of the bone removalinstrument in a plane that is substantially perpendicular to thesubstantially planar medial and lateral reference surfaces. In someembodiments, the guide comprises a guide assembly including a bicruciateretaining tibial trial baseplate and a modular guide removablypositioned in a fixed position with respect to the bicruciate retainingtribial trial baseplate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sagittal view of a distal portion of a femur.

FIG. 2 is a perspective view of a proximal portion of a tibia.

FIG. 3 is a sagittal view of the distal femur of FIG. 1 after a distalresection.

FIGS. 4 and 5 show a distal femoral trial positioned against theresected surface of the distal femur of FIG. 3.

FIG. 6 is a perspective view of the distal femoral trial of FIGS. 4 and5.

FIGS. 7A through 7F show several anterior and sagittal views of afemoral implant, inferior portions of the femoral implant, and a distalfemoral trial.

FIG. 8 shows a distal femoral trial positioned in the joint spacebetween the distal femur and proximal tibia.

FIG. 9 schematically illustrates using a distal femoral trial to gaugefor flexion contracture.

FIGS. 10 through 14D illustrate various kits of distal femoral trials.

FIGS. 15 through 20 show various configurations of distal femoral trialsand the use of such distal femoral trials as gauges.

FIG. 21 is a sagittal view of a distal portion of a femur after a boxbone cut.

FIG. 22 is a sagittal view of a femoral trial positioned on the distalfemur after the box bone cut of FIG. 21.

FIG. 23 through 29 illustrate various methodologies and apparatus forremoving a sulcus portion of a distal femur.

FIG. 30 shows the distal femur after resection, along with an unpreparedproximal tibia.

FIG. 31 illustrates another use for a distal femoral trial.

FIG. 32 illustrates another use for a distal femoral trial.

FIG. 33 illustrates another use for a femoral trial.

FIGS. 34A through 34G are various views of an alignment block.

FIGS. 35 and 36 show another embodiment of an alignment block.

FIGS. 37A through 37E are various views of an extramedullary rodconnector.

FIG. 38 shows the alignment block of FIG. 34 pinned to a proximal tibia,and an extramedullary alignment rod associated with the alignment blockby the extramedullary rod connector of FIG. 37.

FIGS. 39A through 39C show additional views of the alignment block ofFIG. 35.

FIGS. 40A through 40E are various views of a secondary alignment block.

FIGS. 41 A through 43B show another embodiment of a secondary alignmentblock.

FIGS. 44A through 44C show another embodiment of a secondary alignmentblock.

FIGS. 45A through 45C show various views of a medial tibial resectionguide.

FIGS. 46 through 48 show other embodiments of medial tibial resectionguides.

FIGS. 49A through 49E show various configurations of a stylus.

FIGS. 50A through 51 B show other stylus embodiments.

FIGS. 52A and 52B show two examples of tibial implant baseplates.

FIGS. 53 and 54 show an alignment block pinned to a proximal tibia, andan extramedullary alignment rod associated with the alignment block byan extramedullary rod connector.

FIGS. 55 through 59 illustrate various methodologies for positioning,re-positioning, adjusting and/or checking the position and/ororientation of various embodiments of alignment blocks on a proximaltibia.

FIGS. 60 through 74 illustrate various methodologies for positioning,re-positioning, adjusting and/or checking the position and/ororientation of various embodiments of medial tibial resection guides andstyli with respect to a proximal tibia.

FIGS. 75 through 87 illustrate various methodologies and apparatus formaking plateau and/or eminence resections on the proximal tibia.

FIGS. 88 through 98 illustrate various methodologies and apparatus forevaluating a medial plateau resection on the proximal tibia.

FIGS. 99 through 107 illustrate various methodologies and apparatus formaking a lateral plateau resection on the proximal tibia.

FIGS. 108 through 112 show various views of a tibial trial baseplate.

FIGS. 113 through 159 illustrate various apparatus and methodologies forpunching a keel cavity in the proximal tibia, removing an anteriorportion of an eminence on the proximal tibia, and gauging clearancearound the resected eminence of the proximal tibia.

FIGS. 160 through 162 illustrate an alternative embodiment for makingvertical eminence resections on the proximal tibia.

DETAILED DESCRIPTION OF DRAWINGS

The following description of the non-limiting embodiments shown in thedrawings is merely exemplary in nature and is in no way intended tolimit the inventions disclosed herein, their applications, or uses.FIGS. 1-30 illustrate examples of methods and apparatus for preparing adistal femur for a femoral implant during a knee arthroplasty. FIGS. 31to 162 illustrate examples of methods and apparatus for preparing aproximal tibia for a tibial implant during a knee arthroplasty.

Femoral Resections

There is a strong relationship between femoral attachment locations ofsoft tissues and the articulation between the tibia and femur. As ageneral matter, it can be shown that for knee implant designs relyingmore on contrived means of kinematic control and stability rather thanon the native soft tissue structures, kinematic patient outcomes areless sensitive to mismatch between, for instance, the inferior/superiorposition of the native femoral articular surfaces and the implantedfemoral articular surfaces, although such mismatches can still besignificant in some instances. When more native structures are preservedin order to provide kinematic control and stability (e.g., withbi-cruciate retaining implants), however, the preservation of thefemoral joint line can become more important to patient outcome, atleast in some situations.

Currently, the common practice is to favor resection of the distal femurto the level of the trochlea, rather than by measuring a resection depthfrom the medial femoral condyle. It may be preferable, however, in atleast some cases, to utilize methods and apparatus that counteract anytendency to resect the distal femur at a level other than the thicknessof the distal femoral implant. For example, it may be preferable toresect an amount equivalent to the thickness of the distal femoralimplant as measured from the distal medial (and/or lateral) condyle,which may better account for the mesial attachment sites on the femur ofthe posterior and/or anterior cruciate ligaments. It may also bepreferable in at least some cases to utilize methods and apparatus thatallow for early trialing and assessment of extension space and laxity.Some examples of such methods and apparatus are described below.

Some of the methodologies discussed below also reduce the complicationsof knee arthroplasty procedures by not solving for femoral and tibialdegrees of freedom simultaneously, but instead by preparing the femurfirst, and then subsequently preparing the tibia. By completing all ofthe femoral resections prior to the tibial resections, the surgeon isprovided with a fixed set of values from which he or she can determinethe remaining tibial degrees of freedom. Another benefit of preparingthe femur first provided by some of the methodologies described below isthat they ensure proper kinematics. For proper kinematics, the femoralimplant should generally conform to and articulate with the nativeanatomy well (e.g., natural soft tissues and native tibial cartilage).By separating the femoral resection steps from the tibial resectionsteps, the surgeon has no other input variables with which to makefemoral resection decisions other than input variables provided by thenative femoral anatomy.

A third benefit of preparing the distal femur before the tibia in someof the embodiments discussed below is that a surgeon still has theflexibility of performing a posterior stabilized, cruciate retaining, orbicruciate retaining surgery with little or no time penalty orbone-loss, even after the femoral side has been prepared.

Many of the methods and apparatus described below, however, are notlimited to only femur first techniques, or techniques that achieve allof the above benefits.

FIGS. 1 through 9 illustrate one distal bone cut first method andapparatus for carrying out such a method in relation to the distal femur10 shown in FIG. 1 and the proximal tibia 12 shown in FIG. 2.

FIG. 1 shows the distal femur 10 before resection. FIG. 3 shows thedistal femur 10 after resection to define a resected surface 14 on thedistal femur 10. In some embodiments, the resected surface 14 is at adepth that approximately equals the distal thickness of a femoralimplant 16 for eventual implantation on the distal femur 10. Onenon-limiting example of a suitable femoral implant 16 is shown in FIGS.7a and 7d . The distal femoral resection can be performed usingconventional or non-conventional techniques and apparatus. For instance,a conventional cutting block (not shown) could be navigated using theintramedullary canal and/or pinned to the distal femur with one or more(e.g. two) parallel pins to guide a reciprocating or oscillating saw orother cutting device to make the distal femoral resection. In someinstances it may be desirable to leave the pins on the distal femur 10in the event it becomes necessary to reattach the same cutting block ora different cutting block to re-cut the distal femoral resection.

FIGS. 4-8 show a distal femoral trial 18 and the insertion of the distalfemoral trial 18 between the resected surface 14 on the distal femur 10and an unresected surface on the proximal tibia 12 (such as theunresected surface 20 on the proximal tibia 12 shown in FIG. 2). Asshown in FIGS. 4 through 8, the distal femoral trial 18 includes asuperior, planar surface 22 and inferior, curved surfaces 24. Thesuperior, planar surface 22 is configured for contact with the resectedsurface 14 on the distal femur 10. The inferior, curved surface 24,which includes a medial condylar surface 26 and a lateral condylarsurface 28, is for contact with and at least some degree of articulationwith the unresected surface 20 on the proximal tibia 12. The superior,planar surface 22 may be flat, smooth, or textured for improved frictionwith the bone forming and surrounding the resected surface 14 on thedistal femur 10. As shown in FIGS. 7 a through 7 f, the distal femoraltrial 18 of FIGS. 4 through 8 substantially replicates at least some ofthe shapes and thicknesses defined by the femoral implant 16,particularly at least some of the inferior portions 30 (shown in FIGS. 7c and 7 e) of the femoral implant 16.

In the embodiment shown in FIGS. 4 through 8, the femoral implant 16 andthe distal femoral trial 18 are designed to be used in bicruciateretaining procedures. For instance, as shown in FIG. 6, the distalfemoral trial 18 is substantially U-shaped and defines a gap 38 betweenthe medial and lateral condylar surfaces 26, 28 for receiving at least aportion of the tibial eminence 40 of the proximal tibia 12 (shown inFIG. 2). The tibial eminence 40 includes attachment sites for theanterior and posterior cruciate ligaments. The gap 38 of the distalfemoral trial 18 is sized and positioned to avoid substantialinterference with those ligaments when the distal femoral trial 18 isinserted between the resected surface 14 on the distal femur 10 and theunresected surface 20 on the proximal tibia 12, such an example of whichis shown in FIG. 8.

The distal femoral trial 18 shown also includes an attachment site 32(see FIG. 6) for connecting various tools and other apparatus. Forinstance, as shown in FIG. 8, the attachment site 32 can be used toconnect a handle 34, which in turn can be used to connect other tools,such as the extramedullary alignment rod 36 shown. As shown in FIG. 6,the attachment site 32 may include geometry (e.g., but not limited tonon-circular geometry) that allows items such as the handle 34 to besecured in a fixed angular position (e.g., non-rotating). Othermechanisms could also be employed with respect to attachment site 32 forsecuring items to it in a fixed angular position. For instance,attachment site 32 could facilitate the attachment of a fiducialconstruct used in some computer assisted surgery knee procedures.Examples of other tools and other apparatus that can connect toattachment site 32 are discussed further below.

FIGS. 8 and 9 illustrate one way that the distal femoral trial 18 can beused to evaluate the distal femoral resection. FIG. 8 shows the distalfemoral trial 18 inserted into the space between the resected distalfemur 10 and the unresected proximal tibia 12. Although not explicitlyshown in FIG. 8, the distal femur 10 and proximal tibia 12 of the kneejoint are connected by the anterior and posterior cruciate ligaments, aswell as other anatomy such as the medial collateral ligament, thelateral collateral ligament, and the patellar tendon. By inserting thedistal femoral trial 18 into the joint space, the surgeon can evaluatethe distal femoral resection.

For instance, if the distal femoral trial 18 is one that substantiallyreplicates the shape and thickness of an inferior portion 30 of afemoral implant 16 in at least some geometries, and if the resectedsurface 14 on the distal femur 10 has been cut at a depth thatapproximately equals the distal thickness of the femoral implant 16, thesurgeon can evaluate the expected tightness or laxity of the knee joint(taking into account the tension or laxity of one or more of the abovementioned ligaments and tendons) once the procedure is completed and thefemoral implant 16 implanted and/or can evaluate for flexioncontracture.

FIG. 9 schematically shows how a surgeon might evaluate the knee jointfor flexion contracture. In the technique shown in FIG. 9, whichschematically shows the positioning of a distal femur 10 relative to aproximal tibia 12, once the distal femoral trial 18 is inserted betweenthe distal femoral resection and the unresected proximal tibia, the kneejoint can be extended to a maximum amount of extension allowed by theknee joint. If the degree of maximum extension allowed is less thandesired, less than that of a natural, healthy knee joint, and/or lessthan that of the knee joint of the patient prior to surgery(schematically illustrated by dashed line 300 in FIG. 9), it mayindicate a flexion contracture to the surgeon and that a deeperresection of the distal femur is indicated (e.g. that the knee joint is“too tight”). In such instances, the cutting block may be reattached andthe distal femoral resection could be re-cut for a re-evaluation usingthe same or a different distal femoral trial. If maximum extension isadequate (schematically illustrated by the dashed line 302 in FIG. 9),it may indicate to the surgeon that the level of the distal femoralresection is adequate and does not need to be recut. It should beunderstood that although the dividing line (schematically illustrated bysolid line 304) between flexion contracture and adequate extension isshown in FIG. 9 as occurring at approximately 0 degrees of flexion, thedividing line does not have to be so located, and, depending on theparticular circumstances of the patient or other factors, could be atmore or less than 0 degrees of flexion.

One advantage of the distal femoral trial 18 embodiment shown in FIGS. 4through 9 is that it can be used without having to resect the tibia.Many conventional spacer blocks used in gap balancing and otherevaluations of resections in knee arthroplasty procedures require atleast one resection of both the tibia and femur to function properly.The distal femoral trial 18 shown in FIGS. 4 through 9, on the otherhand, facilitates the evaluation of the resected surface 14 on thedistal femur 10 relative to an unresected surface 20 on the proximaltibia 12, and thereby provides information about the level of theresection absolutely. Since the conventional spacer blocks measure afemoral resection relative to a tibial resection, they can only provideinformation about the spacing between the resections and not about thejoint line orientation and position of the femoral resection relative toother important anatomy of the knee joint.

Therefore, in methods where at least one, if not all, of the femoralresections are made prior to resecting the proximal tibia, the distalfemoral trial 18 of FIGS. 4 through 9 can be used to provide informationabout the distal femoral resection level earlier in the surgery thanconventional spacer blocks. Having access to such information earlier insurgery reduces the likelihood of propagating errors which could resultin poor outcomes and increased surgery time.

Another advantage of the methodologies illustrated by FIGS. 4 through 9over many conventional technologies utilizing conventional spacer blocksis that these conventional techniques and spacers may generate a “falselaxity” in the extension space. For example, false laxity in extensioncan be common when using a conventional spacer block to check flexionand extension gaps after the posterior condyles have been resected,since, in some instances, posterior portions of the condyles providesome tension to the various anatomy constraining and otherwiseinteracting with the knee joint. By using the distal femoral trialsprovided herein, a user is obliged to gauge the extension laxity in anenvironment which is most likely to give correct feedback.

It will be apparent to one of skill in the art that the above describedmethodologies and apparatus can be used to evaluate the distal femoralresection in other ways. For instance, in some embodiments, the distalfemoral trial 18 may allow the surgeon to evaluate in an early stage ofthe procedure (e.g. prior to other substantial resections or disruptionsto the patient's anatomy) the appropriateness of the bicruciateretaining implant and procedure for the particular patient, or if aposterior cruciate retaining, bicruciate sacrificing (e.g., for aposterior-stabilized implant), or other implant/procedure should bepursued instead. In combination with the above described or otherevaluation techniques, the distal femoral trial 18 can be associatedwith a handle 34 and a extramedullary alignment rod 36 (such as shown,e.g., in FIG. 8) to facilitate visualization of mechanical andanatomical alignments. In still other embodiments, distal femoral trialsother than those that replicate or substantially replicate the intendedfemoral implant can be used to evaluate the distal resection or otheraspects of the knee joint in other ways.

In some embodiments, such as the embodiments illustrated in FIGS. 31through 33, the distal femoral trial 18 or other types of femoral trialscan facilitate identifying an appropriate depth on the proximal tibia 12for resection. FIG. 31 shows a tibial depth gauge 98 attached to thehandle 34 for marking (using a surgical marker or other apparatus)indicia 100 on the proximal tibia 12 to indicate the desired depth of atibial resection or other information relevant to the knee arthroplasty.Although not shown, in some embodiments, it may be desirable to connectan extramedullary alignment rod 36 or other alignment facilitatingdevices to ensure that the knee joint is in a proper level of extensionor flexion or otherwise appropriately aligned before marking indicia100.

FIGS. 32 and 33 illustrate other apparatus that could be used with thedistal femoral trial 18 (FIG. 32) or another femoral trial 80 (FIG. 33)to indicate tibial depth. FIG. 32 shows an alignment block 102 connectedto the distal femoral trial 18 via an associated handle 34. Thealignment block 102 could be used to mark an indicia on the proximaltibia 12 or, in some embodiments, could be pinned directly to theproximal tibia 12. Because the connection between the distal femoraltrial 18 and the alignment block 102 positions the alignment block 102in a fixed angular position with respect to the distal femoral trail 18,the position of the distal femoral trial 18 and its associated handle 34(and at least to some extent the degree to which the knee joint is inflexion or extension) will control the positioning and orientation ofthe alignment block 102 with respect to the proximal tibia 12, such asits superior/inferior positioning, its varus/valgus angulation, and itsposterior slope. Movement of the knee joint through flexion/extension,however, may at least partially affect some of these positions andorientations of the alignment block 102 with respect to the proximaltibia 12. Accordingly, in some embodiments, it may be desirable to alsouse an extramedullary alignment rod 36 (shown in FIG. 8) or an indicator104 (shown in FIG. 32) to confirm the proper and/or desired positioningof the alignment block 102 on the proximal tibia 12.

FIGS. 10 through 13 illustrate embodiments of surgical kits that includesets 42 of different distal femoral trials 18. For example, FIGS. 11 athrough 11 c schematically show a set 42 of distal femoral trials 18that simulate different femoral implant sizes. The set shown includesthree sizes of distal femoral trials 18: a first to simulate femoralimplants having a size of 1-2 medial-lateral width and a 9.5 mm medialcondyle thickness; a second to simulate femoral implants having a size3-8 medial-lateral width and a 9.5 mm medial condyle thickness; and athird to simulate femoral implants having a size 9-10 medial-lateralwidth and a 11.5 mm medial condyle thickness. In some embodiments, thecondylar radii of each distal femoral trial 18 may generally equal theaverage of each condylar radii within the size range. For instance, thesize 1-2 distal femoral trial may have medial and lateral condylar radiiapproximately equal to the average of size 1 and size 2 medial andlateral radii, respectively. In other embodiments, the condylar radii ofthe distal femoral trial may generally equal the smallest or the largestcondylar radii within a particular femoral implant size range. Forinstance, the second distal femoral trial 18 (representative of femoralsizes 3-8) may have medial and lateral condylar radii approximatelyequal to that of a size 3 (smallest within size range) or a size 8(largest within size range) femoral implant.

In another example, a set of distal femoral trials 18 are providedwithin a surgical kit, each of the distal femoral trials having a sizethat corresponds exactly to a particular femoral implant size. In thisexample, more distal femoral trials may need to be provided to thesurgical kit. However, if each distal femoral trial is representative ofa single femoral implant size, then there is no need to average themedial and lateral distal radii or choose an medio-lateral width torepresent an entire size range with a single distal femoral trial.Therefore, evaluations of laxity and maximum extension may be made moreaccurately at the expense of providing a larger number of distal femoraltrials to the surgical kit.

FIG. 10 shows a set 42 of distal femoral trials 18 that are modular. Inthe embodiment of FIG. 10, each distal femoral trial 18 includes abaseplate 44 that can be connected to a pair of modular shims 46 to forma distal femoral trial 18 of a particular size.

FIGS. 12 and 13 show sets of modular distal femoral trials that usebaseplates 44 and shims 46 to vary specific geometries of the distalfemoral trial 18. For instance, in the embodiment of FIGS. 12 a through12 h, shims 46 facilitate modifying the thickness of the medial andlateral condylar portions of the distal femoral trial. In some uses, theset of modular distal femoral trials illustrated in FIG. 12 may help toaccount for cartilaginous and bony deficiencies in the articular surfaceof the tibia and/or femur, abnormalities, or other deviations (orpatient specific morphology of the femoral condyles) while evaluatingthe distal femoral resection. FIGS. 13 a through 13 l show a set ofmodular distal femoral trials in which the modular baseplates 44 can beused to vary the overall thickness of the distal femoral trial as wellas or alternatively to varying certain angular geometries of the distalfemoral trials, such as the varus/valgus angle or flexion/extensionangles of the distal femoral trial. FIGS. 14 a through 14 d show anotherexample of a set of distal femoral trials in which the baseplate 44itself can be modular, allowing medial and lateral portions of thebaseplate to be changed independent of the other portion. In someembodiments, the baseplates 44 shown in FIGS. 14 a through 14 d could beused individually (e.g. just a medial portion or just a lateral portion)for various purposes, such as for use in unicondylar knee arthroplasty.

In yet other embodiments, the distal femoral trials may includeadjustment mechanisms that allow portions of the distal femoral trialsto be expanded and/or contracted with respect to other portions toadjust the size, thicknesses, angular geometries or other geometries ofthe distal femoral trial.

As shown in FIGS. 15 through 20, in some embodiments, the distal femoraltrial 18 can be used as a gauge for gauging and/or settinginternal/external rotation, anterior/posterior position, and/or size ofthe distal femoral trial 18 with respect to the resected surface 14 onthe distal femur 10. This gauging functionality may facilitate thesurgeon's visualization or planning for how the femoral implant 16 willbe positioned and oriented on the distal femur 10 at the end of theprocedure.

The distal femoral trial 18 shown in FIGS. 15 through 20 includesvarious references that indicate a position of the distal femoral trial18 with respect to the distal femur 10 and the resected surface 14 onthe distal femur 10. For instance, posterior edges 48 of the inferiorcurved surface of the distal femoral trial 18 may be used to referencethe posterior edges 50 of the resected surface 14 on the distal femur 10(as shown in FIG. 17). Paddles 56 may extend substantially perpendicularfrom posterior portions of the distal femoral trial 18 to referenceposterior portions of the medial and lateral condyles 58 of the distalfemur 10. Windows 52 extending through the distal femoral trial 18 maybe used to reference the medial and lateral epicondyles 54 of the distalfemur 10. Another window or windows 60 can be used to indicate theposition of the distal femoral trial 18 with respect to an AP axis 62 ofthe distal femur 10 and/or a central anterior V point 64 of the resectedsurface 14 on the distal femur 10. Other references, such as indiciamarkings on the distal femoral trial, could also be used either bythemselves or in conjunction with windows, paddles and other referencesdescribed above. In some embodiments, anterior surfaces or edges of thedistal femoral trial 18 could be used to reference anterior edges of thedistal femoral resection 14.

In some embodiments, posterior edges 48, windows 52, paddles 56, windows60 and/or other references may be used (in various combinations) togauge the internal/external rotation of the distal femoral trial 18 withrespect to the distal femur 10, which may be used, in some instances, tovisualize and/or plan for the final positioning of the femoral implant16 on the distal femur 10.

The distal femoral trial 18 shown in FIGS. 15 through 20 can also beused to gauge femoral size and AP position. Many of the same referencesdescribed above, such as the posterior edges 48, paddles 56, and windows60 can be used to gauge size and position. Other references on thedistal femoral trial may also be useful, such as, for instance, therelative position of medial and lateral edges 66 of the distal femoraltrial 18 with respect to medial and lateral edges 68 of the resectedsurface 14, or the relative position of a deployable arm 70 or arms (orindicia, not shown, on a deployable arm or arms) with respect to themedial and lateral edges 68, which may be useful in identifying orevaluating a medial-lateral sizing of the femoral implant. As shown inFIGS. 19 and 20, an anterior stylus 72 can be associated with the distalfemoral trial 18 (in the embodiment shown in FIGS. 19 and 20, bypositioning the anterior stylus 72 at the attachment site 32 of thedistal femoral trial 18) to reference the position of the anteriorcortex 74 of the distal femur 10.

Once a desired position and/or rotation of the distal femoral trail 18with respect to the distal femur is achieved, if desired, the surgeoncan create indicia on the distal femur to record that information forfuture use in the procedure. For instance, the distal femoral trial 18shown in FIGS. 15 through 20 includes openings 78 to receive bone pins,a surgical marker or a cutting device that could mark or place indiciaon the distal femur.

In some embodiments, after an evaluation of laxity and extension orother aspects of the distal femoral resection is complete, aconventional “box-bone cut” may be provided to the distal femur 10 asillustrated in FIG. 21. The box-bone cut may be created by placing afive-in-one cutting block on the distal femoral resection, makingposterior bone cuts to the medial and lateral condyles, making posteriorchamfer bone cuts to the medial and lateral condyles, making an anteriorbone cut to the distal femur, making an anterior chamfer bone cut; andthen, if appropriate, making an anterior “roll-on bone cut” on thedistal femur 10 between the anterior chamfer bone cut and the anteriorbone cut. The roll-on bone cut generally allows a femoral componenthaving converging posterior and anterior bone cuts to be implantedeasily without binding. In some embodiments, the indicia on the distalfemur 10 created using the gauging functionality of the distal femoraltrial 18 could be used to position the five-in-one cutting block.

FIG. 22 shows a femoral trial component 80 having a bone-engagingsurface matching said box bone cut installed onto the distal femur 10.The femoral trial component 80 may be provided with a femoral cuttingguide configured to receive and guide a notched cutter (as describedbelow for FIGS. 23 to 28), another type of cutter (as described belowfor FIG. 29) or other features discussed further below. In someembodiments, such as the embodiment shown in FIGS. 23 through 25, thefemoral cutting guide is a separate component 82 that can be securedwith respect to femoral trial component 80 (such as shown in FIGS. 23through 25 and 29). In other embodiments (such as shown in FIGS. 26through 28), the femoral cutting guide is an integral part of thefemoral trial component 80. In some embodiments (not shown) the femoralcutting guide can be a separate component that is not used with thefemoral trial component 80.

In the embodiment shown in FIGS. 23 through 25, the femoral trial 80 andcomponent 82 are used in combination with the notched cutter 84 toremove a distal sulcus portion of the distal femur 10 adjacent to theACL and PCL. FIGS. 26 through 28 show a femoral trial 80 with anintegral femoral cutting guide used with a notched cutter 84. Thenotched cutter 84 shown in the Figures is an elongated chisel thatextends along longitudinal axis 86 (see, e.g., FIG. 24) and includes aleading cutting edge 88. The leading cutting edge 88 has a medialportion 90, lateral portion 92 and a central portion 94 between themedial and lateral portion. The central portion 94 is substantiallyrecessed into the notched cutter, which, in some embodiments may lowerthe force required to cut the distal sulcus portion while also loweringthe chance that the anterior or posterior ligaments could be damagedduring the resection (see, e.g. FIG. 28). The notched cutters 84 shownin the Figures form a U or V shaped leading cutting edge, although othershapes are also possible.

The notched cutters 84 shown in the Figures include flanges 96 thatextend substantially parallel to the cutter's longitudinal axis 86. Theflanges 96 may interact with channels, grooves or other structures oneither the femoral trial 80 or the separate component 82 to guide and/orlimit the movement of the notched cutter 84 along the longitudinal axis.In some embodiments, tips of the flanges and/or structures incorporatedinto the femoral trial 80 or the separate component 82 act to limit thelongitudinal movement to prevent the notched cutter 84 from cutting toodeeply.

FIG. 29 illustrates that other types of cutters and cutting guides canbe used to cut the distal sulcus portion. FIG. 30 shows the distal femur10 once all of the resections described above have been made.

Tibial Resections

One problem faced when performing bicruciate-retaining TKA proceduresthat is of potential significance to at least some of the embodimentsdescribed herein is the complexity of the tibial resections. Thiscomplexity stems from at least two factors, relating to the preservationof the cruciate ligaments.

A first factor is that there are more important degrees of freedomrelating to bicruciate-retaining arthroplasty procedures than fortypical posterior-stabilized or PCL-retaining arthroplasty procedures.For instance, in total knee arthroplasty, objects such as resectionguides and other instrumentation in three-dimensional space have 6degrees of freedom, including three translational degrees of freedom andthree rotational degrees of freedom. At least three additional variablesor “forms” may also apply in TKA procedures, including femoral implantsize, tibial implant size, and tibial insert thickness. For aposterior-stabilized or cruciate-retaining arthroplasty procedure, onlythree degrees of freedom (1 translational and 2 rotational) are usuallyconsidered important. For many, although not necessarily all,bicruciate-retaining arthroplasty procedures, there are at least threeadditional degrees of freedom which are considered important (i.e., 1translational, 1 rotational, and 1 “form”). These three additionaldegrees of freedom arise due to constraints imposed by preservation ofthe eminence to which the cruciate ligaments are attached.

A second factor of potential relevance is that bicruciate retaining kneearthroplasty requires precise surgical technique. The trade off with abicruciate-retaining technique is that of an increased risk ofmechanical complications such as stiffness or implant loosening due tothe complexity of the surgery, in exchange for healthier postoperativepatient mobility and function. The additional degrees of freedomnecessary to perform successful bicruciate-retaining procedures demand agreater degree of accuracy than conventional posterior stabilized orposterior cruciate retaining total knee arthroplasty.

Properly controlling and managing the abovementioned degrees of freedomand other factors during surgery is one of the keys to a clinically andcommercially successful bicruciate retaining arthroplasty. Clinicalsuccess often depends on the ability of a surgeon to accurately andproperly implant a well-designed prosthesis in order to achieve theadvantages provided by the well-designed prosthesis. Commercial successoften depends on the ability of the surgeon to accurately and properlyimplant a well-designed prosthesis with confidence and speed. Some,although not necessarily all, of the embodiments described hereinaddress these concerns.

As stated previously, of all knee arthroplasty procedures, the risksassociated with tibial resection degrees of freedom (i.e., varus/valgusangle, posterior slope angle, and resection depth) are greater forbicruciate-retaining arthroplasty procedures than forposterior-stabilized or posterior cruciate-retaining procedures. This isbecause varus/valgus angle, posterior slope angle, and resection depthdirectly affect the operation of the cruciates in guiding joint motion.Moreover, as stated previously, the risks associated with the additionaldegrees of freedom specific to bicruciate retaining arthroplasty(particularly, internal/external rotation angle and medial/lateralposition of the tibial plateau and eminence resections) can includesevere penalties for error, including, but not limited to compromisedstructural integrity of the tibial eminence, compromised joint motion,and/or compromised cortical rim coverage. Errors associated with any ofthe 5 degrees of freedom associated with a bicruciate retainingprocedure may present a surgeon with complex judgment decisions (such asto favor achieving the best possible cortical coverage over providingmaximum preservation of the tibial eminence and its anterior andposterior cruciate ligament attachment sites). Such judgment decisionsmay be for instance, whether or not to re-cut a bone to correct aperceived error, or to simply let the error remain. Re-cutting decisionscontribute to an increase in both time and complexity, and maysubsequently increase the likelihood of propagating further errors.

Embodiments of the bicruciate retaining total knee arthroplastytechniques and instrumentation described herein presents to surgeons atruly complex surgery in a simplified format through thoughtfulorganization, reduction and readily available information. As will bediscussed hereinafter, these embodiments may provide, in part, animproved method of preparing a proximal tibia during total kneearthroplasty and apparatus thereof. The methodologies and apparatusdescribed below can be generally divided into three stages: controllingdegrees of freedom; making resections; and then performing finishingsteps.

Controlling degrees of freedom can generally include one or more of thesteps of: roughly setting tibial resection depth, setting a neutral (orreference) varus/valgus angle for the medial and lateral tibial plateauresections, setting a neutral (or reference) posterior slope for themedial and lateral tibial plateau resections, fine-tuning the posteriorslope angle and/or varus/valgus angle for the medial and lateral tibialplateau resections, setting medial-lateral positioning of the medial andlateral eminence bone cuts, setting an internal-external rotation anglefor the medial and lateral eminence bone cuts, if desirable, determiningan appropriately-sized tibial eminence width (related to implant size),and fine tuning the depth for both the medial and lateral tibial plateauresections.

Making resections can generally include one or more of the steps of:making a medial tibial plateau resection, making medial and lateraltibial eminence bone cuts, performing a medial plateau balance check,performing a lateral tibial plateau resection, and performing a trialreduction to assess range of motion, joint stability, and soft tissuetension.

Finishing steps can also generally include one or more of the steps of:punching a keel cavity into the cancellous bone of the proximal tibia,and making an anterior eminence bone cut and an anterior tibial plateauresection to remove an anterior block portion of the tibial eminence,removing bone at eminence corners, and implanting a tibial component.

1. Controlling Degrees of Freedom

This section begins by introducing some of the instruments and otherapparatus and describing some aspects of their structure and design thatare used to control tibial degrees of freedom in accordance with some ofthe knee arthroplasty methodologies discussed herein. Later parts ofthis section discuss non-limiting examples of how those instruments andother apparatus are used to control tibial degrees of freedom.

a. Alignment Block

FIGS. 34 a through 34 g show various views of an alignment block 102that can be used, in some embodiments, as a fundamental instrument toprovide such a neutral/reference tibial foundation. The alignment block102 includes a body 106 through which several pin receiving openings 108extend for pining the alignment block 102 to the proximal tibia 12. Thealignment block 102 also includes a bench 110 with a bench connector 112positioned superiorly on the body 106. The bench connector 112 shown inFIGS. 34 a through 34 g is substantially planar, and, as shownparticularly in FIGS. 34 a and 34 c, includes a plurality of indexfeatures 116, the purpose of which will be described further below.

The alignment block 102 shown in FIGS. 34 a through 34 g, particularlyas shown in FIGS. 34 d through 34 f, allows adjustment of the benchconnector 112 in superior and/or inferior directions relative to theproximal tibia 12. As shown in FIGS. 35 and 36 (which show a somewhatdifferent embodiment of the alignment block 102) the alignment block 102may include a set screw 114 that can be loosened or tightened torespectively allow adjustment of the bench 110 in superior and inferiordirections. As also shown in FIGS. 35 and 36, portions of the bench 110can fit into and be guided by grooves or other structures in the body106 to maintain the alignment of the bench 110 with respect to the body106 as it slides in superior and inferior directions. In otherembodiments, other structures and mechanisms could be employed inaddition to or instead of the structures and mechanisms shown in FIGS.35 and 36 to guide the movement and selectively fix the position of thebench 110 with respect to the body 106.

FIGS. 37 through 39 illustrate apparatus for connecting anextramedullary alignment rod 36 to an alignment block 102. FIGS. 37 athrough 37 e show various views of an extramedullary rod connector 118that can be temporarily associated with the alignment block 102, such asis shown in the embodiment illustrated in FIG. 38. The extramedullaryrod connector 118 includes a slot 120 sized and aligned to receive theplanar bench connector 112 of the alignment block 102 and an aperture124 sized and aligned to receive alignment rod 36, which can be securedin the aperture 124 by thumb screw mechanism 126. The slot 120 includesa spring tensioner 122 that, in addition to or instead of the geometryof the slot 120 itself, helps to hold and maintain the angular alignmentof the extramedullary rod connector 118 with respect to the benchconnector 112 (i.e. to maintain an alignment of the extramedullary rodconnector 118 on the planar bench connector 112 such that anextramedullary rod 36 held by the extramedullary rod connector 118 issubstantially perpendicular to the planar bench connector 112).

The geometries and structures of the planar bench connector 112, theslot 120 and/or the spring tensioner 122 allow, in the embodiment shownin FIGS. 37 and 38, the sliding translation and/or rotation of theextramedullary rod connector 118 with respect to the planar benchconnector 112 in several degrees of freedom, while maintaining asubstantially perpendicular alignment of the extramedullary rod 36 tothe planar bench connector 112. In some embodiments, this adjustabilityof the extramedullary rod 36 with respect to the alignment block 102 mayadvantageously allow alignment of the extramedullary rod 36 with axesand/or features of the proximal tibia 12 even though the alignment block102 may be offset from such features. For instance, in some instances itmay be desirable to align the extramedullary rod 36 along thelongitudinal axis of the tibia at the tubercle of the proximal tibia 12,while offsetting the alignment block 102 from such tubercle.

Alignment blocks and extramedullary rod connectors other than thoseshown in FIGS. 34 and 37 could also be used with the methodologies andapparatus described herein. For instance, either the extramedullary rodconnector 118 shown in FIG. 37 or another type of extramedullary rodconnector could be connected at other locations and to other structureson alignment block 102. As another example, FIGS. 35, 36 and 39illustrate an alignment block with a built-in connector for anextramedullary rod and with a differently shaped bench 110.

In some embodiments, an alignment block and extramedullary rod connectorcould be a single piece, or a pair of components that function as asingle piece, with one or both of the components including structure(such as pin receiving apertures) for securing the alignment block andextramedullary rod assembly to the tibia. In some instances, pinreceiving apertures or other securing mechanisms can define elongatedslots that allow adjustment in some degrees of freedom whileconstraining the assembly onto the tibia in other degrees of freedom.

b. Secondary Alignment Block

FIGS. 40 a through 40 c illustrate an adjustment instrument or secondaryalignment block 128 that can be secured to the alignment block 102 shownin FIGS. 34 a through 34 g. The secondary alignment block 128 includes afirst slot 130 and a second slot 132. The first slot 130 is sized andpositioned to receive the planar bench connector 112 of the alignmentblock 102, and, in some embodiments, can be a receiver structure havingan alignment axis. The second slot 132 is sized and positioned toconnect to a medial tibial resection cutting guide, as discussed below,or, in some embodiments, with additional or other components.

In the embodiments of FIGS. 40 a through 40 c, both the first and secondslots 130 and 132 are associated with spring tensioners 134, which may,in the case of slot 130, facilitate the frictional engagement betweenslot 130 and the bench connector 112, while still permitting translationand rotation of the secondary alignment block 128 with respect to thealignment block 102 in certain degrees of a freedom, but whilemaintaining other fixed alignments between the two blocks 102 and 128. Apair of pins 136 extend through at least slot 130, which may, in someembodiments, interact with the index features 116 of the bench connector112 to help retain a desired position and orientation of the secondaryalignment block 128 on the bench connector 112.

FIGS. 41 through 43 illustrate another embodiment of a secondaryalignment block 128 that can be attached to alignment blocks 102, suchas ones shown in FIGS. 35, 36 and 39. The secondary alignment block 128of FIGS. 41 and 42 includes a groove or other structure (not shown) toreceive the T-shaped bench connector 112 of the alignment block 102 ofFIGS. 35, 36 and 39, which constrains, at least to some degree, themovement of this secondary alignment block 128 with respect to thealignment block 102 of FIGS. 35, 36 and 39. Rather, the secondaryalignment bock 128 itself is adjustable in certain degrees of freedomthat allow an upper portion 138 to rotate and translate with respect toa lower portion 140 of the secondary alignment block 128 shown in FIGS.42 a through 42 c while maintaining the alignment of the two portions inother degrees of freedom. As shown in FIG. 43, this secondary alignmentblock 128 includes a pivot 142 and a lock 144 to facilitate therotational and translational adjustment of the upper portion 138 to thelower portion 140, and securing the position and orientation of theupper portion 138 with respect to the lower portion 140 once a desiredposition and orientation are achieved. The pivot 142, which may be ascrew or other mechanism, is positioned in an oblong or oval track inthe lower portion 140. The secondary alignment block 128 shown in FIGS.41 through 43 also includes spring fingers 190 (on superior, inferior orother surfaces) that can, in some embodiments, facilitate frictionalengagement between the secondary alignment block 128 and otherinstrumentation and components, and/or between upper and lower portions138, 140 of the secondary alignment block 128 itself.

As illustrated by these alternative embodiments, the specific manner inwhich the secondary alignment block 128 can be translated and rotatedwith respect to the alignment block 102 is not necessarily important,and a variety of structures and mechanisms can be used to facilitateadjustment in certain degrees of freedom (e.g., without limitation,translation and rotation in a single plane), while preserving otheralignments between the alignment block 102 and secondary alignment block128 (e.g., without limitation, translations and rotations outside of thesingle plane). The embodiments shown in the Figures create “planar”joints that allow simultaneous and limited medial/lateral translationsand internal/external rotations while maintaining other alignments, suchas posterior slope angles and superior/inferior positioning. Althoughthe embodiments shown include planar joints defined by a singleconnection between two components, other structures and mechanisms couldalso be used to create “virtual” planar joints with similar properties.The purpose of these structures and mechanisms for allowing adjustmentin some degrees of freedom (such as medial/lateral position andinternal/external rotation), while limiting movement or rotation inother degrees of freedom, will be described further below.

Returning to the embodiment shown in FIGS. 40 c through 40 e, slots 130and 132 extend through the secondary alignment block 128 at fixed anglesto one another, and the secondary alignment block 128 may be part of aset of secondary alignment blocks 128 having different fixed anglesbetween the two slots 130 and 132 (e.g. 0 degrees, 3 degrees, 5degrees), with such fixed angles being marked on the secondary alignmentblocks 128 such that the surgeon and assistants can differentiatebetween the various blocks 128. As will be described further below, thedifferent fixed angles allow the surgeon to a select a desired fixedposterior slope for the plateau resections on the proximal tibia 12.Although not shown in the Figures, the slot geometry of the secondaryalignment blocks, or other features of the secondary alignment blocks,could vary to allow selection of a desired varus/valgus angle, either inaddition to or alternatively from the selection of a desired posteriorslope angle.

The secondary alignment blocks 128 shown in FIGS. 40 c through 40 elimit control of posterior slope angle to only a few discrete, limitedoptions which are mutable without the need for re-cutting in order toprovide accurate and reproducible bone cuts with conventional surgicalsaw blades and other cutting blocks.

However, it is envisaged that secondary alignment blocks 128 could beprovided with means for incrementally or infinitesimally adjusting aposterior slope angle. FIGS. 44 a through 44 c illustrate an embodimentof a secondary alignment block 128 that can adjust the posterior slopeangle. Such embodiments may comprise indicia 146 on upper, lower, and/orside portions of transverse alignment block to provide the surgeon withinformation relating to small changes in posterior slope angle. Indiciamay comprise, without limitation, a series of markings, grooves, laseretchings, colored bands, printed symbols, and lines. The upper and lowerportions of the secondary alignment block 128 shown in FIGS. 44a through44c are curved to allow the portions to rotate with respect to oneanother, thereby adjusting the posterior slope angle of the alignmentblock. A set screw or other appropriate mechanism may be included tosecure the secondary alignment block in a desired posterior slope.

It is believed that with time and experience with the disclosedbicruciate-retaining surgical technique, surgeons will begin toappreciate the limited number of options for setting posterior slopeangle, and prefer a particular posterior slope angle for all proceduresbased on whatever philosophies he or she adopts and his or her ownobservations.

c. Medial Tibial Resection Cutting Guide

FIGS. 45 a through 45 c illustrate an embodiment of a medial tibialresection guide 148 for attachment to a secondary alignment block 128,such as the secondary alignment blocks 128 shown in FIGS. 40 a through40 e. The medial tibial resection guide 148 shown in these Figuresincludes a central body portion 150 that is configured to be a supportconnection that will connect the medial tibial resection guide 148 to acorrespondingly shaped connection feature or features on a secondaryalignment block 128. In the specific example of the secondary alignmentblocks 128 shown in FIGS. 40 a through 40 e and the medial tibialresection cutting guide 148 shown in FIGS. 45 a through 45 c, the secondslot 132 of the secondary alignment block 128 receives a lower portionof the central body portion 150, and a slot 152 receives the portion ofthe secondary alignment block 128 positioned superior to the second slot132. The interaction between these structures and slots on the twocomponents may, in some embodiments, mean that the position andorientation of the medial tibial resection cutting guide 148, and thestructures and components on it, will be constrained, in at least somedegrees of freedom, by the position and orientation of the secondaryalignment block 128 (such degrees of freedom including, for instance,medial/lateral position, internal/external rotation, posterior slopeangle, and tibial depth). The reason for these constraints will bediscussed further below.

The medial tibial resection guide 148 shown in FIGS. 45 a through 45 cincludes a medial cutting guide surface 154 for guiding a cutting ormilling instrument to resect a medial portion of the proximal tibia 12.As shown in these Figures, the medial cutting guide surface 154 is partof a slot extending through a medial portion of the medial tibialresection guide 148 with superior and inferior surfaces to constrain themovements of a cutter in superior and inferior directions, although, inother embodiments, a single non-capturing cutting guide surface 154 mayonly be necessary. The medial tibial resection guide 148 of theseFigures also includes a medial resection opening 156 and a lateralresection opening 158 for receiving pins to secure the medial tibialresection guide 148 to the proximal tibia and for other purposesdescribed further below. Openings 156 and 158 are oriented insubstantially the same direction and angulation as the slot 152, andthus will be oriented in substantially the same direction and angulationas the secondary alignment block 128 shown in FIGS. 40 a through 40 cwhen the medial tibial resection guide 148 is connected. As shown inFIG. 45 c, a line tangent to the bottom of openings 156 and 158 isgenerally coplanar with the medial cutting guide surface 154.

FIGS. 46 through 48 illustrate alternative embodiments of medial tibialresection guides 148. FIG. 46 illustrates a medial tibial resectionguide that includes both medial and lateral cutting guide surfaces. FIG.47 illustrates another possible configuration for a medial tibialresection guide (including that the medial tibial resection guide can beused for lateral resections as well), and that different configurationsand positions for the resection openings are possible. FIG. 48illustrates another possible configuration for a medial tibial resectionguide, with different structures for attaching the guide to secondaryalignment blocks or other components.

d. Stylus

FIGS. 49 a through 49 e illustrate a stylus 160 that can be used withmany of the methodologies and apparatus described herein. The stylus 160includes a body 162 for connecting the stylus 160 to otherinstrumentation, such as, but not limited to, the medial tibialresection guide 148 shown in FIG. 45 a. In this particular embodiment, aslot 164 (with a spring tensioner positioned therein) in the stylus body162 is configured to receive a portion of the medial tibial resectionguide 148 shown in FIG. 45 a, with an inferior portion 166 of the stylusbody 162 protruding into the slot 152 of the medial tibial resectionguide 148. In such an embodiment, as illustrated by, for example, FIG.74, both portions of the stylus body 162 and portions of the secondaryalignment block 128 protrude into the slot 152 of the medial tibialresection guide 148, creating a single assembly in which thesecomponents are in fixed positions (in at least some translational androtational degrees of freedom) with respect to one another and can betranslated and/or rotated in at least some degrees of freedomsimultaneously. As shown by the Figures and as will be appreciated byone of skill in the art, other connector constructs are also possible tocreate similar or other assemblies of alignment blocks, cutting guidesand styli. As described in further detail below, various stylusembodiments can also be connected to other instrumentation, trials,other apparatus, or anatomy relevant to knee arthroplasty proceduresother than just alignment blocks and cutting guides.

As shown in FIG. 49 a, the body 162 of stylus 160 defines a referenceplane 168 and a connection axis 170. The stylus 160 shown also includestwo indicator members 172 and 174 pivotally mounted to the body 162 (asillustrated by FIGS. 49 a through 49 e). In some embodiments, theindicator members 172 and 174 can rotate about the connection axis 170in planes that are substantially parallel to the reference plane 168,although, in other embodiments, the indicator members 172 and 174 can bemounted to the body 162 in fixed orientations and/or in non-parallelorientations. Depending on the particular use of the stylus 160, severaluses of which are described below, the indicator members 172 and 174 mayfunction as alignment indicators, cutting guides (e.g. an outer guidesurface 176 on one or both of the indicator members 172 and 174),attachment points for other instruments, or for other functions.

As mentioned earlier, three variables that may be specific tobicruciate-retaining surgical procedures are: 1) medial-lateralpositioning of the eminence resections, 2) internal-external rotation ofthe eminence resections, and 3) eminence width. These particularvariables can create a large learning curve for surgeons who need tofeel comfortable and competent during a surgical procedure.

For some of the stylus 160 embodiments discussed herein, degrees offreedom reflected by options for eminence width can be significantlyreduced, if not eliminated entirely. Through empirical measurements ofthe medial-lateral aspect of the anterior cruciate attachment points, ithas been determined that that, in some embodiments, the width of theeminence resections may be set at one of two sizes. In some embodiments,the eminence widths of said two sizes may be approximately 19 mm or 22mm, depending on the size of the tibial implant used (such as is shownin FIGS. 52 a and b). Thus, in one example, if a tibial implant to beused in a surgical procedure has a size within a first size range (e.g.,sizes 1-6), then a first eminence width is used (e.g., a 19 mm eminencewidth). In another example, if a tibial implant to be implanted has asize within a second size range (e.g., sizes 7-8) larger than said firstsize range, then a second larger eminence width is used (e.g., a 22 mmeminence width). It should be noted that more or less than the two sizesand widths other than what is explicitly described are anticipated, asare other widths for each particular size.

In the embodiments shown in the Figures, the indicator members 172 and174 extend substantially parallel to one another, and define planarsurfaces that are substantially parallel to one another as well as tothe reference plane 168. In some embodiments, such as the embodimentsdiscussed immediately above, the spacing of the two indicator members172 and 174 may be defined by the width of a tibial eminence receivinggap 180 on a tibial baseplate 178 (such as the tibial baseplates 178shown in FIGS. 52 a and b). In some embodiments, stylus 160 may includemodular indicator members for achieving different spacings between theindicator members to conform to different sizes of tibial baseplates orfor other reasons. As yet another alternative, different styli may beprovided that include differently spaced indicator members, or havingindicator members of different widths. In still other embodiments, thesame indicator members can be used to guide saws of different widthssimply by using both the inner and outer surfaces of the indicatormembers 172 and 174.

FIGS. 50 and 51 illustrate an alternative embodiment of a stylus 160with a slightly different configuration and different mechanism forconnecting to other components. Other stylus embodiments are alsopossible. For instance, in some embodiments, indicator members couldinclude captured slots or other structures for capturing, and not justguiding, the movement of a reciprocating cutter or other cuttermechanism.

As discussed further below, various embodiments of styli can be used asalignment and/or cutting guides in a wide variety of configurations,and, in some embodiments, it may be desirable that the connectorconstruct employed by the stylus is such that a single stylus can beconnected to a wide variety of different instrumentation, components andother knee arthroplasty apparatus.

e. Positioning the Alignment Block

According to some embodiments, tibial preparation begins by firstestablishing a neutral/reference tibial foundation from which to beginthe procedure. The purpose of providing a neutral tibial foundationearly on in the procedure is to roughly set two neutral degrees offreedom (i.e., neutral varus/valgus angle and neutral posterior slopeangle) before later fine-tuning and/or setting other degrees of freedom.In some embodiments, the neutral foundation could also roughly set otherdegrees of freedom, such as resection depth. Providing a neutral tibialfoundation generally serves as a good starting point, in at least someembodiments, for subsequent tibial preparation steps. In someembodiments, the step of positioning the alignment block 102 establishesa neutral tibial foundation. As used herein, a “neutral” or “reference”tibial foundation could include foundations set a zero degrees to aparticular degree of freedom (such as zero degrees in varus/valgus orzero degrees of posterior slope), but, in some embodiments could alsoinclude “non zero” neutral foundations.

As illustrated by FIGS. 53 through 59, the surgeon can position, orient,and secure in place the alignment block 102 in a wide variety of ways.FIGS. 53 and 54 illustrate the use of an extramedullary alignment rod 36and an extramedullary rod connector 118 to position and orient thealignment block 102. In this embodiment, the longitudinal axis of thealignment rod 36 may be secured at the patient's ankle and aligned atleast roughly parallel to the mechanical axis (in one or both ofsagittal and coronal planes) of the tibia at the tibial tubercle or atother locations. Because the connections between the particularextramedullary rod 36, extramedullary rod connector 118, and alignmentblock 102 embodiments shown in FIGS. 53 and 54 will position the benchconnector 112 of the alignment block 102 substantially perpendicular tothe longitudinal axis of the alignment rod 36, when the alignment rod 36is aligned to be roughly parallel to the mechanical axis of the tibia insagittal and coronal planes, the bench connector 112 will lie in a planehaving a zero degree varus/valgus angle and a zero degree posteriorslope angle to the tibia. As shown in FIGS. 53 and 54, the connectionsbetween these components also allow the alignment block 102 to be offset(in medial or lateral directions) from the tibial tubercle while stillaligned in neutral varus/valgus and posterior slope angles. In theembodiment shown in FIGS. 53 and 54, the alignment block 102 ispositioned with only a rough (or no) concern for the precisesuperior/inferior positioning of the alignment block 102 with respect tothe tibial plateau, and such positioning can be addressed at a laterpoint in the procedure, such as by slidably adjusting thesuperior/inferior positioning of the bench connector 112 with respect tothe alignment block 102 or repositioning the alignment block 102 itself.

FIG. 55 illustrates an embodiment where the superior/inferiorpositioning of the alignment block 102 is taken into account at thisstage in the procedure. As shown in FIG. 55, the alignment block 102 canbe simultaneously associated with both an extramedullary rod 36 and asecondary alignment block 128, with the extramedullary rod 36facilitating positioning and orienting the alignment block 102 inneutral varus/valgus and posterior slope angles, and the secondaryalignment block 128 facilitating positioning the alignment block 102 ata desired superior/inferior position. For instance, in the embodimentshown in FIG. 55, a superior surface of the secondary alignment block128 can be aligned with indicia 100 to set the alignment block 102 at adesired superior/inferior position on the proximal tibia 12. Asdiscussed above and shown in FIGS. 31 through 33, the position forindicia 100 can be determined in a variety of ways, which may, in someembodiments, correspond to a desired resection depth for the medialand/or lateral tibial plateau resections, or in other embodiments,correspond to a position having a fixed offset from the desiredresection depth, both of which may, in some embodiments, be determinedbased on the level of the distal femoral resection.

In still other embodiments, such as shown in FIG. 56, a desiredsuperior/inferior position for the alignment block 102 can be set usinga stylus 182 that references the level of the tibial plateau or astructure of interest on the tibial plateau. In still other embodiments,such as shown in FIG. 57, a distal femoral trial 18 can be used toposition and orient the alignment block 102, at least roughly, at bothneutral varus/valgus and posterior slope angles, as well as at a desiredsuperior/inferior position. In such embodiments, it may be desirable(although not required) to use an extramedullary alignment rod 36 (suchas by connecting it to the handle 34) to ensure that the alignment block102 is appropriately positioned, particularly with respect to theposterior slope angle of the alignment block 102, since smallangulations in flexion or extension of the distal femoral trial 18 couldaffect the posterior slope of the associated alignment block 102. FIG.58 illustrates a similar embodiment, which utilizes a femoral trial 80to facilitate positioning and/or alignment of the alignment block 102.

FIG. 59 illustrates another embodiment for aligning an alignment block102, which utilizes a bi-forked paddle stylus 184 in conjunction with anextramedullary alignment rod 36 to position and orient the alignmentblock 102. The bi-forked paddle stylus 184 may be placed on a medialand/or lateral portion of the unresected proximal tibial plateau andused as a visual aid in setting a rough medial-lateral position of thealignment block 102 and a rough resection depth. The positioning of thebi-forked paddle stylus 184 and/or the alignment rod 36 with respect tothe alignment block 102 and the tibia 12 may be adjusted in order todetermine and set the alignment rod 36 and alignment block 102 at adesired neutral varus/valgus angle and neutral posterior slope angle.Once these neutral angles are set, the alignment block 102 may besecured to the alignment rod 36 with a securing means such as a cam andlever (such as illustrated in FIGS. 35, 36 and 39), thumbscrew,setscrew, spring loaded ratchet or detent, or equivalent means providedon the alignment block 102 or a component associated with the alignmentblock 102. The alignment block 102 may then be secured to an anteriorportion of the proximal tibia 12 (e.g., by pinning) and can serve as aneutral tibial foundation for a remainder of the procedure. After thealignment block 102 is pinned to the tibia 12, the bi-forked paddlestylus 184 may be removed from the adjustable portion of the alignmentblock 102, and the alignment rod 36 may optionally be removed from thealignment block 102, tibia 12, and ankle in order to create more spacefor the surgeon to work.

f. Positioning the Medial Cutting Block

In some embodiments, the next step in tibial preparation is positioninga medial cutting block (or a combined medial/lateral cutting block) toguide one or more tibial plateau resections and (optionally) verticaleminence resections. In some instances, such as with particularbicruciate retaining tibial implants, degrees of freedom relevant to themedial/lateral position and internal/external rotation of the plateauand/or vertical eminence bone cuts may be highly interrelated, suchthat, in some embodiments, it may be preferable to set these degrees offreedom simultaneously. In some instances, setting these degrees offreedom individually could be an iterative and time-consuming process.

FIG. 60 shows one embodiment of a cutting guide assembly including analignment block 102 pinned to the proximal tibia, to which a secondaryalignment block 128 is mounted, which is in turn connected to a medialtibial resection guide 148 as well as a stylus 160. In this particularembodiment, the orientation of the alignment block 102 pinned to theproximal tibia 12 establishes the varus/valgus alignment of the variousresection guides provided by the medial tibial resection guide 148 andthe stylus 160. The orientation of the alignment block 102 alsoestablishes, in connection with the particular secondary alignment block128 chosen the posterior slope angle of the medial tibial resectionguide 148. The superior/inferior positioning of the planar benchconnector 112 establishes the resection depths for the tibial plateauand vertical eminence resections. As shown, for example, by the variousFigures and embodiments described above and below, this is only oneexample of the many ways the various components described herein couldbe connected and used to control the various degrees of freedom for thetibial resections.

In the particular embodiment of FIG. 60, the medial/lateral position andthe internal/external rotation of the secondary alignment block 128 withrespect to the planar bench connector 112 of the alignment block 102establishes the medial/lateral position and internal/external rotationof the tibial plateau and vertical eminence resections. The planar jointformed by the bench connector 112 and the first slot 130 (see, e.g.,FIGS. 40c through 40e ) of the secondary alignment block 128 allows thesecondary alignment block 128 (and thus the medial tibial resectionguide 148 and stylus 160) to be translated and rotated in the planedefined by bench connector 112, such that both the medial/lateralposition and internal/external rotation of the secondary alignment block128/medial tibial resection guide 148/stylus 160 assembly can beadjusted simultaneously, potentially avoiding the need for iterativeadjustments of these two degrees of freedom separately from one another.Interactions between the index features 116 (see, e.g., FIG. 34 a) onthe alignment block 102 and the pins 136 (see, e.g., FIG. 40 a) of thesecondary alignment block 128, as well as friction between the springtensioner 134 (see also FIG. 40 a) of the secondary alignment block 128and the planar bench connector 112 of the alignment block 102 may, atleast to some extent, facilitate maintaining the position andorientation of the medial tibial resection guide 148/stylus160/secondary alignment block 128 assembly once placed in a desiredposition and orientation, prior to pinning the medial tibial resectionguide 148 (or other components) to the proximal tibia 12.

As shown in FIGS. 61 a through 61 d, the indicator members 172, 174 onthe stylus 160 can be used while adjusting the position and orientationof the secondary alignment block 128 to visualize the mesial position ofthe medial and lateral tibial plateau resections, as well as themedial/lateral position and internal/external rotation of the verticaltibial eminence resections (such resections being described furtherbelow). This visual feedback to the surgeon may facilitate positioningthe medial tibial resection guide 148 and stylus 160 optimally withrespect to the tibial eminence 40, the anterior and posterior cruciateligament attachment sites, and other relevant anatomy.

As shown in FIGS. 62 through 69, stylus 160 can also be used, in someembodiments, to check other alignments and orientations of the anatomy,instrumentation, trials and other apparatus used in knee arthroscopyprocedures. For instance, as shown in FIGS. 62 through 69, stylus 160can be used to visualize alignment with respect to a femoral trial 80 onthe distal femur 10, such as, without limitation, various alignmentswith respect to an intra-condylar notch 292 in the femoral trial 80(FIGS. 62 through 67) or alignments with respect to a trochlear region294 formed in an anterior face of the femoral trial 80 (FIGS. 68 through69), which, as shown in these Figures, may include alignments withrespect to an axis of the femur or femoral trial, as illustrated by thevertical lines on the femoral trial 80 shown in FIG. 69. In theseembodiments, the stylus 160 is shown connected to a secondary alignmentblock 128 and a medial tibial resection guide 148, although stylus couldbe connected to other instrumentation, apparatus or anatomyalternatively. In these embodiments, the stylus 160 is shown being usedwith the knee joint in various states of flexion and extension.

For the embodiments shown in FIGS. 68 and 69, varus/valgus alignment ofthe femoral trial component relative to the medial plateau resectionguide 148 can be assessed by rotating the arms of the stylus 160upwards, to a vertical position in such a way that they are adjacent toa trochlear region 294 of the femoral trial 80. This step may beperformed to verify passive correctability and avoid impingement of thetibial eminence and femoral intercondylar notch. If a surgeon hassignificant concerns over the peripheral fit of the tibial baseplate onthe circumferential cortical rim of the resected tibia, then alternativemethods and means for setting medial-lateral positioning andinternal/external rotation of the eminence and tibial bone cuts (such asillustrated in FIG. 74) may be preferred.

As shown in FIG. 71, resection depth may be checked with an angel wingslot gauge 296 associated with the medial tibial resection guide 148.The angel wing slot gauge 296 is representative of the thickness of atibial implant. A variety of mechanisms and techniques, as discussedearlier, can be used to roughly set and/or fine tune resection depth.

FIGS. 70 through 74 show non-limiting examples of other possibleassemblies and methods for positioning the medial tibial resection guide148 and/or stylus 160 for the tibial plateau and vertical eminenceresections. FIGS. 70 and 71 show an assembly utilizing a two piecesecondary alignment block 128 (also shown and described in connectionwith FIGS. 41 through 43) that itself can be adjusted in medial/lateraland internal/external degrees of freedom, rather than moving the entiresecondary alignment block 128 with respect to the alignment block 102.FIGS. 72 through 74 illustrate that the position and orientation of thedistal femur when in, for instance, extension, can provide referenceinformation that can be used to position and orient the medial tibialresection guide 148 and/or stylus 160. As shown in these Figures, aconnector 188 can be inserted (e.g., anteriorly) into a distal receivingportion of the femoral trial 80 to connect one or more of the medialtibial resection guide 148, stylus 160 and secondary alignment block 128to a femoral trial 80 or other construct positioned on the distal femur10, which may or may not take into account resected surfaces on thedistal femur 10, and, as such, the position of the femoral trial 80 orother construct on the distal femur 10 can be used to position andorient the apparatus used for the proximal tibia 12 resections. In theembodiment shown in FIGS. 72 and 73, cylindrical bosses on the medialtibial resection guide 148 (or, in other embodiments, on the stylus 160)rest within a track of the connector 188. Generally, anterior-posteriortranslation and flexion/extension angle of the medial/tibial resectionguide 148 relative to both the connector 188 and femoral trial 80 arenot constrained. However, internal-external rotation andsuperior-inferior positioning are generally constrained when the medialtibial resection guide 148 is coupled with the connector 188.

In the embodiment reflected by FIGS. 72 and 73, adjustment portions onthe secondary alignment block 128 and alignment block 102 may beloosened and tightened in an iterative fashion, so that alignment of themedial tibial resection guide 148 is set in a neutral biomechanicalposition when the leg is placed in full extension. Once the neutralbiomechanical position is set, the adjustment portions on the secondaryalignment block 128 and alignment block 102 may be re-tightened, and theconnector 188 may be removed so that the stylus 160 may be attached. Inother embodiments, such as shown in FIG. 74, many of these steps areunnecessary, due to the planar joint connection between the secondaryalignment block 128 and the alignment block 102.

2. Tibial Resections

As mentioned above, tibial resections can generally include one or moreof the steps of: making a medial tibial plateau resection, makingvertical medial and lateral tibial eminence resections, performing amedial plateau balance check, performing a lateral tibial plateauresection, and performing a trial reduction to assess range of motion.These steps, in some embodiments, do not necessarily have to beperformed in this order.

a. Medial Tibial Plateau Resection

Once the medial tibial resection guide 148, stylus 160, and/or secondaryalignment block 128 assembly is placed in a desired position andorientation, one or more of these components can be secured to theproximal tibia 12 using bone pins or other fastening mechanisms. Forinstance, the medial tibial resection guide 148 shown in FIGS. 45 athrough 45 c includes a medial resection opening 156 and a lateralresection opening 158 that guide the placement of bone pins or otherfasteners into the proximal tibia which, in some embodiments, mayperform one or both of the dual functions of (1) securing the medialtibial resection guide 148 to the proximal tibia 12 for stability duringresection, and (2) acting as stops to limit the movement of areciprocating saw or other cutting device. In some embodiments, the bonepins may act as stops to prevent accidental notching of the tibialeminence during medial and/or lateral tibial plateau resections as wellas to prevent making the vertical medial and lateral eminence bone cutstoo deep into the proximal tibia 12, reducing potential stressconcentrations and providing other benefits. These pins, in someembodiments, may be located at intersection points at the base of thevertical eminence resections and the mesial extents of the plateauresections. In some embodiments, such as embodiments that use thedual-bladed reciprocating bone cutting saw described below, a singlebone pin (in either the medial or lateral resection opening 156, 158)can function to limit the depth of both vertical eminence bone cuts.

As shown in FIGS. 75 and 76, once the medial tibial resection guide 148has been pinned to the proximal tibia 12, in some embodiments, othercomponents such as the alignment block 102 and secondary alignment block128 can be removed. As shown in these Figures, if desired, the pinssecuring the alignment block 102 (or other components) to the proximaltibia 12 can be left in place to preserve information about the neutralvarus/valgus, neutral posterior slope, or other information in the eventit is desirable to reattach such components or other components later inthe procedure. As shown in FIG. 76 a, extramedullary rod connector 118and extramedullary alignment rod 36 may, in some embodiments, bedirectly attached to the medial tibial resection guide 148 as anadditional alignment check. In the embodiment shown in FIG. 76 b, theextramedullary rod connector 118 references the medial cutting guidesurface 154 (see FIG. 45 a) to indicate the varus/valgus and posteriorslope angles of the medial tibial plateau resection. In someembodiments, the medial cutting guide could be positioned using anextramedullary rod connector and extramedullary alignment rod alone.

Once the medial tibial resection guide 148 is secured to the proximaltibia 12, a saw or other cutter can be used to perform the medial tibialplateau resection. If a medial tibial resection guide 148 such as theone shown in FIG. 46 is used, a lateral tibial plateau resection mayoptionally also be made at this time.

b. Vertical Eminence Resections

In order to fully remove the medial plateau portion of the proximaltibia 12, at least one generally vertical medial eminence resection mustbe made in addition to a medial plateau resection. As shown in FIGS. 77and 78, the stylus 160 can function as a cutting guide for thesevertical resections, which delineate the medial and lateral boundariesof the preserved tibial eminence. Traditional single bladedreciprocating saws can be used for the vertical resections, although, asshown in FIGS. 77 and 78, dual-bladed reciprocating saw blades 192 canalso be employed to cut both medial and lateral eminence bone cutssimultaneously.

FIG. 82 illustrates an embodiment of a monolithic dual-bladed saw 192,which includes a first elongated reciprocating bone cutting blade 194, asecond elongated reciprocating bone cutting blade 196, and a connector198 connecting the two blades together. The connector 198, which in FIG.82 is “Y” shaped although other shapes are also envisioned, connects thetwo blades 194, 196 together at proximal ends of the blades 194, 196,which extend generally parallel to one another to define cutting planesthat are substantially parallel to one another. In some embodiments,blades 194, 196 are positioned approximately 10 to 30 mm apart from oneanother. In some embodiments, blades 194, 196 are positionedapproximately 19-22 mm apart from one another. Each blade 194, 196includes an inner, planar surface 200 for contact with the planar outersurfaces of indicator members 172, 174 of stylus 160. The inner, planarsurfaces 200 of the blades 194, 196 and the outer, planar surfaces ofindicator members 172, 174 may be substantially smooth, to facilitateeven sliding of the blades 194, 196 on the indicator members 172, 174during use.

In some embodiments, because blades 194, 196 are only connected togetherat their proximal ends, it may be desirable to manufacture the blades194, 196 (or adjust the blades after manufacture) such that they areslightly biased towards one another, such that they are biased incontact with stylus 160 during use, which may provide some stability tothe dual bladed saw 192 during use.

FIGS. 79 through 81 illustrate a modular dual-bladed saw 192 where thefirst and second blades 194, 196 are removably connected to connector198. As shown in these Figures, each blade 194, 196 includes anattachment feature 202, such as but not limited to a “T” shaped shank,that interacts with corresponding structure on the connector 198 tosecured blades 194, 196 in connector 198. FIG. 81 shows that connector198 includes slots 204 sized to receive the “T” shaped shank and alsocapture it at one end (see ref. 206) to secure blades 194, 196 inconnector 198. In the particular embodiment shown, flexing distal endsof the blades inwardly towards one another with respect to their shankswill permit insertion and removal of the shanks into the grooves. Othermechanisms such as, without limitation, one or more set screws, springfingers, ball detents, collets, wedges, clamps, jaws, or any otherfriction increasing or other devices known in the art could be used tosecure blades 194, 196 in connector 198.

In the embodiment shown in FIGS. 79 through 81, first and second blades194, 196 are standard reciprocating surgical bone cutting saw blades,and the attachment features 202 of those blades 194, 196 are designedfor connecting them, albeit one at a time, directly to a reciprocatingsaw (not shown). Accordingly, in at least some embodiments, it will bedesirable for the attachment features 202 of the blades 194, 196 to besubstantially the same size and shape of the attachment feature 208 ofthe connector 198, so that the connector 198 can be used with the sametypes of reciprocating saws.

The dual-bladed saws 192 shown in FIGS. 79 through 82 are configured tomake generally parallel (in both superior/inferior andanterior/posterior directions) resections around the tibial eminence 40,such as illustrated in FIG. 83. This embodiment may be advantageous forcruciate retaining procedures since it allows to resections to be madesimultaneously, thereby saving time and also increasing the likelihoodthat the two resections will be parallel with respect to one another. Inother embodiments, however, it may be desirable to vertically resect thetibial eminence in non-parallel manners, such as to create generallytrapezoidal prism shaped tibial eminences.

For instance, FIG. 84 shows one set of non-parallel vertical tibialeminence resections where the vertical resections extend at an obtuseangle relative to their corresponding horizontal plateau resections. Insome embodiments, a trapezoidal prism shaped resected tibial eminence 40may reduce stress concentration at the eminence base and facilitateintroducing compression and shear forces between the tibial baseplateand the eminence walls to prevent the eminence from breaking off underhigh ligament tensions. These compression and shear forces between thetapered eminence bone cuts and the tibial baseplate may be present evenwhen the two are separated by a cement mantle. It should be understoodby those of ordinary skill that a single reciprocating saw would likelybe used to create the angled medial and lateral eminence bone cuts shownin FIG. 84, and could be formed using medial tibial resection guides 148such as shown in FIG. 85.

Eminence bone cuts may also be oriented to form of a wedge in atransverse plane along a superior-inferior axis of the tibia asillustrated in FIG. 86, which may be created with the assistance of acutting block such as shown in FIG. 87. These and other foreseeablecombinations of eminence bone cut orientations are envisaged as possibleembodiments.

In some embodiments, it may be desirable before making final verticaltibial eminence bone cuts to make provisional vertical tibial eminencebone cuts in order to asses the planned position of the tibial baseplatewith respect to the tibial eminence and other tibial anatomy. There aregenerally three criteria for setting tibial degrees of freedom. A firstconsideration is the orientation of the femur in full extension. Asecond consideration is the location of attachment points of thecruciates (i.e., the ACL and PCL) on the tibial eminence. A thirdconsideration is the final positioning of the outer periphery of thetibial baseplate relative to the cortical rim of the resected tibialplateau (i.e., making sure the baseplate does not overhang, and thatbone “fit” and “coverage” is optimized). The second and thirdconsiderations become increasingly more important as the clearancebetween the eminence gap of the tibial baseplate and the actual tibialeminence width becomes smaller.

According to some methods such as shown in FIGS. 160 through 162,provisional eminence bone cuts may be made. For instance, medial andlateral generally vertical eminence bone cuts may be made at slightlywider locations than the width than is required for the final tibialimplant. In other words, enough eminence bone is preserved during theprovisional eminence bone cuts that secondary eminence bone cuts may beadjusted and re-cut in an orientation more conducive to optimal corticalcoverage (e.g., optimizing the third consideration described above).Once the provisional medial and lateral eminence bone cuts have beenmade (and prior to trial reduction steps), a trial tibial baseplate 306having an eminence gap wider than the provisional eminence cuts may beplaced on the resected tibial plateaus and shifted to a position wherecortical bone coverage is optimal. In the particular embodiment shown inFIGS. 160 through 162, baseplate 306 references (using a “bump” as shownor other suitable structures or mechanisms) an anterior aspect of theproximal tibia. The eminence may then be re-cut as necessary to providebetter cortical coverage of the trial tibial baseplate. Theaforementioned cutting steps may be facilitated by a special “largewidth” provisional stylus 160, or by a stylus provided with extra thickarms to increase the eminence width between the medial and lateraleminence bone cuts. Thus, with these methods, information about thecortical coverage is available prior to finalizing the permanent shapeand position of the tibial eminence.

In some embodiments, a dual bladed reciprocating saw blade 192 can beused instead of a stylus 160, to function as an indicator or alignmentguide for positioning and orienting a medial tibial resection guide 148.In such embodiments, since a stylus 160 is not used, it may be desirableto use a medial tibial resection guide 148 that has vertical eminencebone cut guides incorporated into it (such as the guide shown in FIG.85).

c. Medial Plateau Balance Check

In some embodiments, although not necessarily all, it may be desirableto evaluate the medial plateau resection before making the lateralplateau resection. As described below, evaluation of the medial plateauresection prior to making the lateral plateau resection (or in otherembodiments, evaluation of a lateral plateau resection prior to making amedial plateau resection) can help reduce the risk that the otherplateau resection will have to be cut twice by ensuring that before thesecond plateau resection is made, its position has been optimized forthe best kinematic, kinetic, and biomechanical outcomes. Additionally,or alternatively, evaluation of the medial or lateral plateau resectionmay, in some embodiments, be done in a manner to reduce the likelihoodthat the same side of the tibial plateau will have to be resectedmultiple times. In still other embodiments, the evaluations describedbelow (and the apparatus for performing such evaluations) can bemodified for use after both the medial and lateral resections, which mayreduce the likelihood that the plateau resections will have to beresected multiple times.

There are at least two situations where re-cutting a medial plateauresection (or other plateau resection(s)) may be necessary. In someinstances, re-cutting may be necessary when a tibial trial implant(e.g., a medial tibial trial insert) sits too proud on the proximaltibia. If reducing the thickness of the tibial insert cannot resolve theproblem, the medial plateau resection needs to be relocated slightlydeeper to make more room for the thickness of the tibial implant. Asecond instance where re-cutting is typically necessary is when theposterior slope angle of the medial plateau resection needs adjustment.For example, if there is too much laxity or tightness in extension orflexion, then the posterior slope angle may be too shallow or too steep.

As used herein, “evaluation” of the medial plateau or other resection(s)can take the form of a variety of different checks on the suitability ofits positioning and/or orientation, or the potential need to re-cut orredo the resection at a different depth or orientation (e.g. at adifferent posterior slope angle). In some embodiments, evaluation cantake the form of articulating a femoral trial on a medial tibial trial,which may, in some embodiments, allow the surgeon to check the balance,tightness, and/or laxity of the knee joint in flexion and extension. Insome embodiments, such evaluations can involve using these or additionaltibial trials from a kit of tibial trials to simulate the effect of are-cut of the resection or the use of a different tibial implant on thebalance of the knee joint, which may, in some embodiments, reduce therisk associated with having to re-cut the resection. FIGS. 88 through 98illustrate non-limiting embodiments of methods and apparatus useful insuch evaluations.

FIG. 88 illustrates one embodiment of the use of a tibial trial insert210 for the evaluation of a medial plateau resection 212, an example ofwhich is shown in FIG. 83. As shown in FIG. 88, the tibial trial insert210 is associated with a handle 214, which includes a planar inferiorsurface (see, e.g. FIGS. 90-91) for referencing the medial plateauresection 212. As shown in FIGS. 90-91, the inferior surface 216 of thetibial trial insert 210 is designed to connect to or rest in the handle214. When the tibial trial insert 210 is connected to the handle 214,and the handle positioned on the medial plateau resection 212, thesuperior surface 218 of the tibial trial insert 210 replicates (at leastin some aspects) the expected final positioning and orientation of acorresponding articulation surface of a tibial implant(baseplate+insert) implanted on the medial plateau resection 212. Insome embodiments, the tibial trial insert 210 is part of a kit ofinserts which can simulate: 1) the final position and orientation of anarticular surface of a tibial implant without re-cutting bone, and 2)the final position and orientation of an articular surface of a tibialimplant after a predetermined type of re-cut (e.g., changes to depthonly, posterior slope angle only, or combinations thereof), withoutactually re-cutting bone.

FIGS. 92 through 95 illustrate tibial trial insert options according tosome embodiments of the invention for simulating different implantoptions or surgical decisions (e.g. re-cutting). FIG. 92 shows a medialtibial trial insert 210 that simulates the use of a different tibialinsert that has a bevel to compensate for a medial plateau resectionthat has too much or not enough posterior slope. The medial tibial trialinsert 210 of FIG. 92 may be part of a kit of several trial inserts inwhich the angles and orientations of the bevels on those inserts vary inorder to mute the adverse effects of a primary medial plateau resectionhaving an inadequate posterior slope angle and avoid re-cutting thetibia. In other words, each medial tibial trial insert 210 within theset shares the same or a similar implant thickness, (e.g., theapproximate thickness measured at the thinnest portion of the insert)but each insert within the set incorporates a different bevel angle tocompensate for primary resections having a poor posterior slope angle.

FIG. 93 shows a medial tibial trial insert 210 that simulates the use ofa different tibial insert that has a different thickness to compensatefor a medial plateau resection that is either too superior or inferior(e.g. if the knee joint is too tight or too loose in both flexion andextension). The tibial trial insert 210 of FIG. 93 may be one of a setof inserts 210 that share the same or similar posterior slope angles,but have different overall thicknesses.

FIG. 94 shows a medial tibial insert 210 that simulates re-cutting themedial plateau resection at a different posterior slope angle (e.g. ifthe knee joint is too tight or too loose in one of flexion orextension). These inserts 210 are termed “re-cut simulation” trialinserts, and they generally provide the surgeon with a way to trial asif he or she has made a re-cut before any re-cuts are made. In this way,the surgeon may investigate his or her options for compensating forlaxity or tightness in flexion or extension without needing to actuallycut bone to do so. This may lower the chances that no more than tworesections to the medial plateau and one resection to the lateralplateau will be needed during the procedure. In some embodiments, themedial tibial insert 210 shown in FIG. 94 may correspond to thesecondary alignment block 128 shown in FIG. 97 that will facilitateresecting the medial tibial plateau resection at a different posteriorslope angle from the secondary alignment block 128 shown in FIG. 96 thatwas originally used in the first resection of the medial tibial plateau.The tibial trial insert 210 of FIG. 94 may be one of a set of inserts210 that have different posterior slope angles to simulate re-cuttingthe medial plateau resection at a different posterior slope angle.

FIG. 95 shows a medial tibial insert 210 that simulates re-cutting themedial plateau resection at a different resection depth (e.g. if theknee joint is too tight or too loose in both flexion or extension, andimplant thickness cannot be adjusted to adequately compensate). Forinstance, a surgeon may choose to perform range of motion and laxitytests before re-cutting a second plateau resection slightly deeper andgenerally parallel to the first resection. In some embodiments, themedial tibial insert 210 shown in FIG. 95 may correspond to thesecondary alignment block 128 shown in FIG. 98 that will facilitateresecting the medial tibial plateau resection at a differentsuperior/inferior position from the secondary alignment block 128 shownin FIG. 96 that was used in the first resection of the medial tibialplateau. The tibial trial insert 210 of FIG. 95 may be one of a set ofinserts 210 that have different thicknesses to simulate re-cutting themedial plateau resection at a different depths.

It should be noted that the tibial trial inserts discussed above may beused alone or in combination in order to trial virtually any surgicalscenario prior to making a second medial plateau resection. Combinationsof trial tibial insert simulations may include inserts that representchanging both implant thickness and posterior slope angle simultaneouslyor other combinations of implant attributes and resection levels andangulations. In other words, tibial trial inserts may be provided tosimulate the steps of implanting a thicker or thinner tibial implant(e.g., tibial insert) after re-cutting the medial tibial plateau at adifferent posterior slope angle than the first resection.

d. Lateral Tibial Plateau Resection

FIGS. 99 through 107 illustrate embodiments of a lateral cutting guide220 for guiding a cutting tool while making a lateral plateau resectionon the proximal tibia 12. Other embodiments include a medial cuttingguide having similar structures and functions to the lateral cuttingguide 220 of FIGS. 99 through 107, but for use in cutting a medialplateau resection on the proximal tibia 12 (e.g. in a technique wherethe lateral plateau resection is made first and the medial plateauresection is second).

The lateral cutting guide 220 shown in FIG. 99 includes a block or body222 defining a horizontal guide member 224 for guiding a cutting tool.In the embodiment shown in FIG. 99, horizontal guide member 224 is aslot with substantially planar superior and inferior surfaces forcapturing and guiding the movement of a cutting tool in a horizontalplane, although, in other embodiments, horizontal guide member could beun-captured (e.g. a substantially planar inferior surface without acorresponding superior surface to capture the cutting tool). In theembodiment shown, the inferior planar surface of horizontal guide member224 is positioned and oriented to be co-planar with the medial tibialplateau resection 212. A paddle 226 or other structure having asubstantially planar reference surface (on an inferior surface notshown) may extend from the body 222 to reference the medial tibialplateau resection 212 and position and orient horizontal guide member224 in substantially the same plane as the reference surface of thepaddle 226 (although, in other embodiments, they can be offset from oneanother in one or both of rotational and translational aspects). Boththe paddle 226 and other portions of the body 222 can include pinreceiving openings 228 to facilitate securing the lateral cutting guide220 to the proximal tibia 12, some of which may be oriented obliquely tofurther stabilize the lateral cutting guide 220 and also positioned intobone that will eventually be resected, minimizing the number of holesleft in the proximal tibia 12 after the procedure.

FIGS. 100 through 103 illustrate two embodiments of a flag pin 230 thatcan be used in connection with lateral cutting guide 220. The flag pins230 shown in FIGS. 100 through 103 include elongated insertion portions232 for insertion into a lateral navigation opening 234 formed in theproximal tibia 12, which can be formed, in some embodiments, by usingthe lateral resection opening 158 of the medial tibial resection guide148 shown in FIG. 45a or in other manners. The elongated insertionportion 232 of the flag pin 230 shown in FIGS. 100 and 101 issubstantially cylindrical. The elongated insertion portion 232 of theflag pin 230 shown in FIGS. 102 and 103 includes, in addition to acylindrical portion, a planar section for insertion into the lateral,vertical eminence bone cut in the proximal tibia 12, which may furtherstabilize and align the flag pin 230 in the proximal tibia 12.

Depending on the particular procedure employed, due to the relativelysmall lateral operating exposure available with a medial incisionapproach, the presence of the laterally retracted extension mechanismand the unique shape of each tibia, it may be important to allow thesurgeon to maneuver the lateral cutting guide 220 to a preferredposition and to provide adequate space to maneuver a cutting tool suchas a saw blade. However, in maneuvering a cutting tool, it may bedesirable to protect the anterior and lateral sides of the eminence frominadvertent notching during the resection. Some embodiments of thelateral cutting guides 220 and flag pins 230 described herein may helpto prevent or reduce the risk of inadvertent notching of anterior andlateral portions of the eminence and to otherwise protect the anatomy ofthe knee joint.

The flag pins 230 shown in FIGS. 100 through 103 may perform threefunctions of potential importance to the lateral tibial plateauresection. First, they may guard against lateral eminence notching.Second, they may provide a planar reference and at least one degree offreedom (e.g., medial-lateral translation, anterior-posteriortranslation, and internal-external rotation) while maintainingpositioning and stability. Third, they create a relieved boundary toguard against anterior eminence notching while still allowing ananterior-medial approach of the saw blade.

Flag pin 230 may include an enlarged head potion 236 defining at leastone substantially planar surface. This substantially planar surface (orsurfaces) may provide a reference for facilitating the appropriatepositioning of the lateral cutting guide 220 (in connection with paddle226) such that the cutting guide 224 is substantially coplanar to themedial plateau resection 212 (such as by its interaction with acorrespondingly shaped flag pin receiving opening 238 in the lateralcutting guide 220) while at the same time allowing some translationaland/or rotational movement between the lateral cutting guide 220 and theproximal tibia 12. In other words, the interaction of the substantiallyplanar enlarged head portion 236 of the flag pin 230 and thecorrespondingly shaped flag pin receiving opening 238 in the lateralcutting guide 220 may act as a planar joint that provides stability andmaintains the lateral cutting guide member 224 in a coplanarrelationship with the medial plateau resection 212 while allowing forother translations and rotations of the lateral cutting guide 220 foroptimum positioning against the proximal tibia 12. FIGS. 105 and 106illustrate how such a planar joint could allow the lateral cutting guide220 to be rotated at an angle ø, which may position the guide 220 closerto the lateral side of the tibia 12 in a more desirable orientation forthe surgeon.

As mentioned above, flag pin 230 may also provide a relieved boundarywhich guards against anterior and other eminence notching while stillallowing an anterior-medial approach of the saw blade. In this respect,an angled leading edge 240 of the enlarged head portion 236 in additionto the elongated insertion portion 232 may act as an additional guide tolimit the movement of a cutter in a mesial direction towards anteriorand lateral aspects of the tibial eminence 40, while not overlyinterfering with the cutting tool's access for the lateral plateauresection. This guiding function of the flag pin 230 is schematicallyillustrated in FIG. 107.

In some embodiments, while referencing the medial plateau resection, thelateral cutting guide 220 may be stabilized using additional oralternative means. For example, in some embodiments, paddle 226 may bethickened or augmented with a spacer block that mates with or restsagainst the femoral trial 80. In other examples, paddle 226 may beinserted into a resection kerf or slot created by the horizontal medialplateau resection bone cut prior to making the generally vertical medialeminence bone cut. In doing so, paddle 226 is captured from above andbelow by native tibial bone.

e. Trial Reduction

FIG. 104 illustrates the proximal tibia 12 after the medial plateauresection 212 and lateral plateau resection 242 have been completed, butbefore removal of an anterior portion of the tibial eminence 40 andbefore punching for the keel of the tibial implant.

Fracture of the tibial eminence can be a possible intra-operative and apost-operative threat to successful bicruciate-retaining arthroplasty.Intra-operatively, trial reduction steps such as evaluating range ofmotion may present a high risk of eminence fracture due the intensity ofvarus/valgus stress tests. Post-operatively, large loads passing throughthe ACL and to the anterior attachment point of the ACL on the tibialeminence may also increase the risk of eminence fracture. In order toreduce these risks, some embodiments described herein provide methodsfor trialing prior to removing anterior portions of the anterioreminence. Means for facilitating trialing prior to removing the anterioreminence may comprise a tibial baseplate 244 that bypasses the anterioraspect of the eminence as shown in FIGS. 108 through 112.

Methods according to some embodiments utilize an “anterior cut last”method for reducing the likelihood of anterior eminence fracture. Atibial baseplate 244 (one embodiment of which is shown in FIG. 108) maybe structured to be positioned on the proximal tibia 12 while providingspace for an intact anterior portion of the tibial eminence 40 (FIGS.108 through 110). A pair of trial inserts 246 can be secured to thetibial baseplate 104 (FIG. 111) to facilitate a trial reduction, balancecheck and range of motion check in connection with a femoral trial (FIG.112). If range of motion and laxity are satisfactory, the finalfinishing steps of punching a keel cavity and removing the anteriorportion of the tibial eminence may, in some embodiments, be performed(discussed in a section further below).

The tibial baseplate 244 shown in FIG. 108 includes a medial baseplateweb 248, a lateral baseplate web 250 (inferior portions of which, notshown, include substantially planar surfaces (co-planar to one another)for referencing the medial and lateral plateau resections), and a bridge252 connecting the two webs 248, 250 together. The tibial baseplate 244defines a gap 254 between the two webs 248, 250 that is sized andpositioned to receive a tibial eminence 40 including anterior andposterior cruciate ligament attachments sites. In some embodiments, thisgap measures approximately 14 to 40 mm in a medial/lateral direction and35 mm to 70 mm in an anterior/posterior direction. The baseplate webs248, 250 can define attachment features to facilitate the connection ofmedial and lateral tibial trial inserts 246 to the baseplate 244 (seeFIG. 111). In some embodiments, for instance, the webs 248 and 250 maybe somewhat resilient and have structure for snapping into correspondinggrooves or other receiving structures in the inserts 246. Any otherdesired mechanisms or structures could be used to secure the inserts 246to the baseplate 244. In still other embodiments, the trial inserts canbe an integral part of the trial baseplate. In still other embodiments,the inserts can just rest in the trial baseplate, and are not attachedto the baseplate.

In some embodiments, the tibial baseplate 244 can be used to gauge andvisualize what the final position of a bicruciate retaining tibialimplant will be on the proximal tibia 12, in order to ensure appropriatecoverage, that the implant will not hang over the cortical rim of theproximal tibia 12, that the clearance between the implant and eminencewill be appropriate, and to check other alignments, clearances andspacings. The medial baseplate web 248 may include a mesial referencesurface 260 for illustrating an extent of a medial, mesial surface ofthe tibial implant, and an outer reference surface 262 for illustratingan extent of a medial, outer surface of the tibial implant. The lateralbaseplate web 250 may include a mesial reference surface 264 forillustrating an extent of a lateral, mesial surface of the tibialimplant, and an outer reference surface 266 for illustrating an extentof a lateral, outer surface of the tibial implant. The tibial baseplate244 may also include one or more datum sites, such as apertures 268 orattachments for other instrumentation discussed below, for marking onthe tibia or otherwise indicating or defining positioning of the trialbaseplate 244 with respect to the proximal tibia 12 once a desirepositioning is obtained.

In some embodiments, such as illustrated in FIGS. 160 through 162, atrial baseplate 306 can be sized and otherwise configured forprovisional eminence cuts that are wider than the final eminence cuts,in order to allow for earlier assessment of cortical rim coverage andeminence clearance.

3. Finishing

As mentioned earlier, finishing steps may generally include one or bothof the steps of: (1) punching a keel cavity into the cancellous bone ofthe proximal tibia 12, and (2) making an anterior eminence bone cut andan anterior tibial plateau resection to remove an anterior block portionof the tibial eminence 40.

In some embodiments, the tibial baseplate 244 used during trialing andassessing range of motion may remain in place for the punching andanterior eminence bone cut steps and can essentially act as the datumreference for the punching and cutting instruments. Depending on thespecific structure, positioning and orientation of the punching andcutting instruments used with the tibial baseplate 244, the tibialbaseplate 244 may be formed with appropriately shaped, positioned andoriented gaps, slots or other openings to permit the punching andcutting instruments to pass through the tibial baseplate 244 and intothe bone of the proximal tibia 12. For instance, the embodiment of atibial baseplate 244 shown in FIG. 110 includes gaps 278 for receivingmedial and lateral portions of a U-shaped punch described below, andincludes a slot 280 (see FIG. 111) that allows a chisel or other cutterto pass for making a horizontal bone cut to the anterior portion of thetibial eminence 40, as also described below.

FIGS. 113 through 157 show various embodiments of a guide 270 that maybe fastened directly to the tibial baseplate 244 and tibia 12 using pinsor other means for securement (such as shown for example in FIG. 149) orindirectly to the tibial baseplate using an intermediate component suchas secondary alignment block 128 or another component (such as shown forexample in FIG. 116). Guide 270 may be used, in some embodiments, toguide punch 276 for forming a keel cavity 272 (see, e.g., FIGS. 124 and140) in the proximal tibia 12 for receiving the keel of a tibialimplant, and, in these or other embodiments, may also be used to guideone or more chisels 282 or other cutters to remove anterior portions ofthe tibial eminence 40 (as illustrated by, for example, FIG. 121).

The precision offered by the tibial baseplate 244 when it is used, insome embodiments, as a control reference for the positioning of theguide 270 and other instrumentation can be desirable, as it can helpensure that there is no mismatch conflict between the tibial eminence 40and the punched keel cavity 272 when the surgeon inserts the finaltibial tray baseplate implant. Since the implant will mate or at leastcorrespond to both portions of the tibial eminence 40 and the punchedkeel cavity 272 in some embodiments, it can be important that the twoare positioned correctly relative to each other so that the implant doesnot bind, become tilted, or sit proud after insertion.

As shown by, for example, the embodiment of FIGS. 133 through 139, theguide 270 has a recessed portion which provides clearance over andaround the anterior portion of the tibial eminence 40. The guide 270also includes structure (such as pair of slots 274 shown for instance inFIG. 125 or other appropriate structure such as a dovetailed guide)configured to guide a punch 276 or other bone removal instrument (e.g.,broach, mill, cutting blade, saw blade, chisel) into the proximal tibia12 in a controlled manner.

In one embodiment (see, e.g., FIGS. 133 through 134), punch 276 isconfigured to create a keel cavity 272 at an insertion angle. The punchmay be asymmetric or symmetric and may comprise one or more wingportions to create a generally “U-shaped” keel cavity. In someembodiments, a smaller punch or broach may be used first to lessen theimpaction force necessary to form the keel cavity 272. As mentionedabove, in some embodiments, the tibia baseplate 244 may define a gap ofappropriate size and shape to receive the U-shaped punch.

In some embodiments, the insertion angle of the punch 276 isnon-perpendicular (in some embodiments obtuse) to the plateau resectionsand matches the keel angle of a tibial implant to reduce the risk ofpunching through or fracturing the anterior cortical bone of the tibia.The guide 270 ensures that the punch 276 travels at a consistentpredetermined angle and orientation during insertion. An alternativeembodiment (not shown) allows for various sections of the keel to bepunched individually.

Because the insertion angle of the punch 276 is not orthogonal to themedial and lateral plateau resections, a user may tend to flex the punch276 when impacting or the punch 276 may tend to extend or bow duringimpact. In order to avoid these problems, in some embodiments, stabilitycan be added to the punch construct by various means. A first means forproviding stability comprises an optional handle as shown in FIGS. 155through 157. In these or other embodiments, further securement may beachieved by attachment of the alignment block 102 to the secondaryalignment block 128 so that the punch guide 270, tibial baseplate 244,secondary alignment block 128, alignment block 102, and/orextramedullary rod 36 can be connected together. By positivelyconnecting all of the aforementioned instruments, enhanced stability isprovided to the guide 270, though it should be noted that use of fewersecuring devices is possible for reduction of complexity and opening ofworkspace. In other embodiments, other combinations of these and otherinstrumentation and other apparatus can be used to position the guide270. In still other embodiments, offset impactors (e.g. having impactsurfaces that are not linearly aligned with an end associated with thepunch) could be utilized instead of or in addition to the abovedescribed mechanisms to maintain appropriate alignment of the punch.

As shown in FIGS. 127 through 132, long drill pins 284 may also bepre-inserted into the tibia to reduce the amount of force necessary topunch the keel cavity (especially at corners of the punch), and reducestress concentrations at the keel cavity corners by rounding out thesharp corners. The long drill pins 284 may also serve as guide pins toaid in guiding and stabilizing the punch 276 at said insertion angle.

The anterior portion of the eminence may be removed before (e.g. FIGS.121 through 126) or after (FIGS. 133 through 139) punching. If theanterior portion of the eminence 40 is removed after the punch 276 isfully seated in the tibia 12, one or more chisel slots 286 may beintegrally provided on any one of: the punch, an anterior portion of thetibial baseplate, or an anterior portion of the guide. If the punchingstep is performed properly prior to anterior eminence removal, in theseembodiments, the chisel slots 286 will be in the optimal position forresecting and removing the anterior portion of the tibial eminence.Multiple captured chisel slots, uncaptured chisel slots, or planar guidesurfaces may be provided on or adjacent to the punch.

In some embodiments, chisel slots may be configured to provide ananterior eminence bone cut that is oriented in a substantially verticalposition as shown in FIGS. 140 and 141. In some embodiments, chiselslots may be oriented to provide an anterior eminence bone cut which ispositioned at angles relative to said substantially vertical position asshown in FIG. 142. In some embodiments, the chisel slots may be orientedwith some internal or external rotation as shown in FIG. 147 to provideangled anterior eminence bone cuts as shown in FIG. 143.

In some embodiments, removing the anterior eminence can make the step ofpunching a keel cavity easier, because there is less bone for the punchto penetrate after the anterior portion of the tibial eminence isremoved. However, removing the anterior eminence after punching willensure that the anterior eminence bone cut, anterior plateau resection,and keel cavity are all properly aligned with respect to each other.Instrument kits according to the invention may be provided with optionsto perform one or both methods. The keel cavity is preferably made usinga single punch; however, a set of two or more punches may be provided toform the keel cavity sequentially, and thereby removing small amounts ofbone at a time. For instance, a preliminary broaching punch having oneor more smaller dimensions than a finishing broaching punch may beprovided to gradually open the keel cavity without fracturing the bone.Preliminary broaching steps may be preferred in cases of very dense orsclerotic tibial bone.

As shown for example in FIG. 138, additional chisel slots 286 may beprovided on an anterior portion of the guide 270 to facilitate ananterior plateau resection. In one preferred embodiment, the anteriorplateau resection is generally oriented substantially horizontally andco-planar to the medial and lateral plateau resections. However, otherembodiments may incorporate chisel slots configured to make an anteriorplateau resection parallel with or at an angle with respect to themedial and lateral plateau resections. The meeting of the generallyhorizontal anterior plateau resection and the generally verticalanterior eminence resection effectively removes an anterior blockportion of the tibial eminence.

Any one of the tibial baseplate, punch guide, and cutting tool may beprovided with a means for limiting travel of the cutting tool such as aflange, a stop portion, a lip, or a step portion, or an interferenceportion. For instance, FIGS. 137 and 138 shows chisels 282 with stops288 formed thereon. Such stops 288 or other structures or mechanisms canbe used to prevent or lessen the likelihood of eminence notching.

Stops 288 or other stopping mechanisms may be calibrated for limiting apenetration depth for both the horizontal anterior plateau resection andthe generally vertical anterior eminence resection. Those mechanisms mayprovide equal or different amounts of chisel depth penetration for theanterior eminence bone cut and anterior plateau resection. In someembodiments, the stop 288 will allow the use of a single chisel for boththe anterior eminence bone cut and anterior plateau resection.

The chisel slots 286 for making the generally vertical anterior eminencebone cuts are shown as integral with the punch 276 in FIGS. 135 through137. They may alternatively be provided in a separate chisel guide blockadapted to cooperate directly with the guide 270 such as shown in theembodiment of FIG. 150. However, making the anterior eminence bone cutthrough a slot that is integral and monolithic with the punch 276 asshown in FIGS. 133 through 139 allows the relationship between theanterior eminence and the punched keel cavity to be held to a tightertolerance, thereby providing a better fit of the tibial implant, and, insome embodiments, although not all, may therefore be preferable. In someembodiments, similar control of the placement of the anterior eminenceis achieved by providing chisel slots on the guide 270. In other words,an anterior eminence chisel may be guided by means for guiding providedon the guide 270 itself. In this way, the generally vertical anterioreminence bone cuts may be made either before or after punching. Themeans for guiding provided on the punch guide may be, for example, acantilevered extension of the punch guide having a guide slot thereon.

After punching a keel cavity and removing the anterior portion of thetibial eminence, the antero-medial and antero-lateral eminence cornersshown in FIG. 153 can be rounded to form eminence radii as shown in FIG.154. The eminence radii generally serve to provide clearance for theinstalled tibial implant, and are made by trimming the sharpantero-medial and antero-lateral eminence corners with a rongeur tool orother desirable tools. Alternatively, eminence radii may be formed bycutting die features formed in the punch.

After the above preparation steps are completed, the prepared proximaltibia 12 may be gauged with a gauge 290 simulating the shape and size ofthe corresponding implant to be installed as shown in FIGS. 158 and 159.The gauge 290 generally serves to provide the surgeon informationrelating to implant fit, and more specifically ensures that when thefinal implant is seated within the prepared keel cavity, it will mateproperly with the eminence, and not interfere or cause interference orbinding with the eminence. After the prepared proximal tibia is gauged,implantation of the final tibial implants may proceed in a conventionalmanner.

Additional Embodiments

In some embodiments, significant cost savings are enjoyed whenmanufacturing the instruments disclosed herein. For example, tibialbaseplates according to some embodiments are both asymmetric andambidextrous; in other words, chirality is not a necessity, but can bepresent if desired, for certain instruments to be used on either left orright legs. For instance, for each tibial baseplate size, a tibialbaseplate may be inverted to work with either a left tibia or a righttibia. The lateral plateau resection guide may also be ambidextrous,meaning it can be used on either a left tibia or a right tibia.

A large number of asymmetric tibial trial inserts creates a need tomanage the large inventory. For example, trials must be provided forboth medial and lateral condyles of both left and right knees. Inaddition, the trials must come in a sufficient number of sizes (e.g.,4-6 size options), thicknesses (e.g., 6 thickness options), andposterior slope angle options (e.g., high, standard, reduced). In someembodiments, up to 192 trial inserts could be necessary to cover asufficient number of surgical options. Some embodiments address thisissue by providing several means for reducing system complexity.According to some embodiments, one means for reducing system complexityis building posterior slope angle options into the tibial baseplatesrather than into the inserts themselves. In this manner, there are onlytwo or so baseplate trials (each having a different slope) for eachparticular tibial implant size. Building posterior slope angle into thetibial baseplates will effectively double the number of necessary tibialbaseplates in the system, (e.g., from 8 to 16); however, will generallyreduce the number of necessary tibial trial inserts by approximately 50%(e.g., from 192 to 96).

It should be noted that adjustability features may be transferredbetween parts. In some instances, for example, the secondary alignmentblock may have superior-inferior adjustment capabilities built in,instead of the alignment block. In other instances, the alignment blockmay be provided with means for selectively or infinitely adjusting theposterior slope of the medial plateau resection, instead of thesecondary alignment block. Moreover, a means for medial-lateraldirection adjustment of the stylus may be provided to any one of thesecondary alignment block, alignment block, or medial plateau resectionguide in some embodiments.

It should also be understood that method steps disclosed herein may beperformed in any order regardless of the order in which they arepresented, and that while a medial cut first method may be preferable insome embodiments, the surgical techniques provided may be adapted for alateral plateau cut first method.

As various modifications could be made to the exemplary embodiments, asdescribed above with reference to the corresponding illustrations,without departing from the scope of the invention, it is intended thatall matter contained in the foregoing description and shown in theaccompanying drawings shall be interpreted as illustrative rather thanlimiting. Thus, the breadth and scope of the claimed invention shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims appendedhereto and their equivalents.

The invention claimed is:
 1. A method comprising: attaching a first instrument to a tibia, the instrument having a substantially planar portion, the substantially planar portion comprising an anterior edge at an anterior side of the first instrument when the first instrument is attached to the tibia; with the first instrument attached to the tibia, coupling a second instrument to the substantially planar portion of the first instrument by receiving the anterior edge of the substantially planar portion in a slot of the second instrument, the second instrument and the first instrument forming a planar joint that allows translation and rotation of the second instrument in a plane relative to the first instrument; adjusting a position of the second instrument relative to the first instrument to place the second instrument in an adjusted position relative to the first instrument; and releasably fixing the second instrument to the first instrument with the second instrument in the adjusted position relative to the first instrument.
 2. The method of claim 1, wherein adjusting the position of the second instrument relative to the first instrument comprises translating the second instrument along the substantially planar portion of the first instrument while the second instrument is attached to the first instrument.
 3. The method of claim 1, wherein adjusting the position of the second instrument relative to the first instrument comprises rotating the second instrument about an axis perpendicular to the substantially planar portion of the first instrument while the second instrument is attached to the first instrument.
 4. The method of claim 1, wherein attaching the first instrument to the tibia comprises pinning the first instrument to an anterior surface of the tibia such that the substantially planar portion of the first instrument extends generally perpendicular to a superior/inferior axis of the tibia.
 5. The method of claim 1, wherein the second instrument comprises a receiving portion that defines the slot; wherein coupling the second instrument to the substantially planar portion of the first instrument comprises inserting the substantially planar portion of the first instrument into the slot in the receiving portion of the second instrument such that the second instrument extends from a superior surface of the substantially planar portion, around the anterior edge of the substantially planar portion, and along an inferior surface of the substantially planar portion; and wherein adjusting the position of the second instrument relative to the first instrument comprises adjusting a position of the second instrument relative to the first instrument while the substantially planar portion of the first instrument extends into the slot.
 6. The method of claim 5, wherein inserting the planar portion of the first instrument into the slot in the receiving portion of the second instrument comprises engaging the substantially planar portion of the first instrument with the receiving portion of the second instrument such that the engagement of the substantially planar portion with the receiving portion limits movement of the second instrument to translation and rotation along a plane defined by the substantially planar portion.
 7. The method of claim 1, wherein the substantially planar portion of the first instrument has a substantially planar superior surface.
 8. The method of claim 7, wherein the substantially planar portion of the second instrument has a substantially planar inferior surface, and wherein the first instrument has a gap beneath the substantially planar inferior surface at an anterior edge, a medial edge, or a lateral edge of the substantially planar portion.
 9. The method of claim 7, wherein the first instrument has a body having a plurality of holes defined through the body along axes substantially parallel to the substantially planar superior surface of the substantially planar portion.
 10. The method of claim 1, wherein the second instrument comprises a spring tensioner; and wherein releasably fixing the second instrument to the first instrument comprises releasably fixing the position of the second instrument relative to the first instrument at least in part through the engagement of the spring tensioner with the substantially planar portion of the first instrument.
 11. The method of claim 1, wherein coupling the second instrument to the substantially planar portion of the first instrument comprises: with the first instrument attached to the tibia, moving the second instrument posteriorly to introduce the substantially planar portion into a slot of the second instrument.
 12. The method of claim 1, wherein the substantially planar portion comprises a superior surface and an inferior surface, the first instrument having a space that is located adjacent the inferior surface and that extends to the anterior side of the first instrument; and wherein coupling the second instrument to the substantially planar portion of the first instrument comprises receiving the substantially planar portion in a slot of the second instrument such that the second instrument has (i) a first portion extending posteriorly along the superior surface of the substantially planar portion and (ii) a second portion extending posteriorly along the inferior surface into the space that is located adjacent the inferior surface.
 13. The method of claim 1, further comprising: coupling one or more indicator members to the second instrument; and positioning the one or more indicator members to extend into a knee joint that includes the tibia; wherein adjusting the position of the second instrument relative to the first instrument is performed while the one or more indicator members extend into the knee joint.
 14. The method of claim 13, wherein positioning the one or more indicator members to extend into the knee joint comprises positioning a first indicator member and a second indicator member to extend into the joint on opposite sides of a tibial eminence of the tibia with at least a portion of the tibial eminence received between the first indicator member and the second indicator member; and wherein adjusting the position of the second instrument relative to the first instrument is performed while the first indicator member and the second indicator member extend into the joint on opposite sides of the tibial eminence.
 15. The method of claim 13, wherein positioning the one or more indicator members to extend into the knee joint comprises: positioning a lateral indicator member to extend along a lateral side of a tibial eminence of the tibia; and positioning a medial indicator member to extend along a medial side of the tibial eminence of the tibia; wherein adjusting the position of the second instrument relative to the first instrument comprises translating or rotating the second instrument along the substantially planar portion of the first instrument while the lateral indicator member extends along the lateral side of the tibial eminence and while the medial indicator member extends along the medial side of the tibial eminence.
 16. The method of claim 13, wherein the one or more indicator members comprise a first indicator member and a second indicator member that extend substantially parallel to each other; and wherein the first indicator member and the second indicator member define a space between the first indicator member and the second indicator member that has a predetermined width.
 17. The method of claim 1, further comprising, while the second instrument is releasably fixed to the first instrument with the second instrument in the adjusted position relative to the first instrument: performing a lateral cut on the tibia that is lateral to an anterior cruciate ligament of the tibia, the lateral cut extending in a superior-inferior direction through a portion of the tibia; and performing a medial cut on the tibia that is medial to an anterior cruciate ligament of the tibia, the medial cut extending in a superior-inferior direction through a portion of the tibia.
 18. The method of claim 17, wherein performing the lateral cut comprises setting a position of the lateral cut based on the adjusted position of the second instrument relative to the first instrument; and wherein performing the medial cut comprises setting a position of the medial cut based on the adjusted position of the second instrument relative to the first instrument.
 19. A method comprising: attaching a first instrument to a tibia, the instrument having a substantially planar portion; with the first instrument attached to the tibia, coupling a second instrument to the substantially planar portion of the first instrument to form an instrument assembly, the second instrument and the first instrument forming a planar joint that allows translation and rotation of the second instrument in a plane relative to the first instrument; coupling one or more indicator members to the instrument assembly; positioning the one or more indicator members to extend along a superior surface of the tibia; adjusting a position of the second instrument relative to the first instrument with the one or more indicator members extending along the superior surface of the tibia, wherein the adjusting places the second instrument in an adjusted position relative to the first instrument; and releasably fixing the second instrument to the first instrument with the second instrument in the adjusted position relative to the first instrument.
 20. The method of claim 19, wherein positioning the one or more indicator members to along a superior surface of the tibia comprises positioning a first indicator member and a second indicator member to extend along opposite sides of a tibial eminence of the tibia; and wherein adjusting the position of the second instrument relative to the first instrument is performed while the first indicator member and the second indicator member extend along the opposite sides of the tibial eminence.
 21. The method of claim 20, wherein positioning the one or more indicator members to extend along a superior surface of the tibia comprises positioning the one or more indicator members to extend substantially parallel to each other with the first indicator member and the second indicator member defining a space between the first indicator member and the second indicator member that has a predetermined width.
 22. A method comprising: attaching a first instrument to a tibia, the instrument having a substantially planar portion; coupling a second instrument to the substantially planar portion of the first instrument, the second instrument and the first instrument forming a planar joint that allows translation and rotation of the second instrument in a plane relative to the first instrument; adjusting a position of the second instrument relative to the first instrument to place the second instrument in an adjusted position relative to the first instrument; releasably fixing the second instrument to the first instrument with the second instrument in the adjusted position relative to the first instrument; performing a vertical cut on the tibia that extends in a superior-inferior direction through a portion of the tibia, the vertical cut being aligned with respect to the tibia based at least in part on the adjusted position of the second instrument relative to the first instrument.
 23. The method of claim 22, wherein coupling the second instrument to the substantially planar portion of the first instrument comprises receiving the substantially planar portion of the first instrument in a slot of the second instrument; and wherein releasably fixing the second instrument to the first instrument comprises engaging a tensioner member with the substantially planar portion.
 24. The method of claim 22, wherein coupling the second instrument to the substantially planar portion of the first instrument comprises receiving the substantially planar portion of the first instrument in a slot of the second instrument to form a planar joint that permits translation of the second instrument along the substantially planar portion along multiple different axes while the substantially planar portion extends into the slot. 